Form 485BPOS VANGUARD VALLEY FORGE

Fund Summary

Investment Objective

With 60% of its assets, the Fund seeks to track the performance of a benchmark index that measures the investment return of the overall U.S. stock market. With 40% of its assets, the Fund seeks to track the performance of a broad, market-weighted bond index.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Investor Shares or Admiral Shares of the Fund.

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Examples

The following examples are intended to help you compare the cost of investing in the Fund’s Investor Shares or Admiral Shares with the cost of investing in other mutual funds. They illustrate the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund’s shares. These examples assume that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense examples, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 44% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of two benchmark indexes. The Fund invests by sampling its target indexes, meaning that it holds a range of securities that, in the aggregate, approximates the full indexes in terms of key characteristics.

With approximately 60% of its assets, the Fund seeks to track the investment performance of the CRSP US Total Market Index, which represents approximately 100% of the investable U.S. stock market and includes large-, mid-, small-, and micro-cap stocks regularly traded on the New York Stock Exchange and Nasdaq. The Fund samples the Index by holding a broadly diversified collection of stocks that, in the aggregate, approximates the full Index.

With approximately 40% of its assets, the Fund seeks to track the investment performance of the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, which represents a wide spectrum of public, investment-grade, taxable, fixed income securities in the United States—including government, corporate, and international

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dollar-denominated bonds, as well as mortgage-backed and asset-backed securities—all with maturities of more than 1 year. At least 80% of the bond portion of the Fund is invested in bonds held in the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, and all of the Fund’s bond holdings are selected through the sampling process. The bond portion of the Fund maintains a dollar-weighted average maturity consistent with that of the Index, which generally ranges between 5 and 10 years and, as of December 31, 2016, was 8.3 years.

Principal Risks

The Fund is subject to the risks associated with the stock and bond markets, any of which could cause an investor to lose money. However, because stock and bond prices can move in different directions or to different degrees, the Fund’s bond holdings may counteract some of the volatility experienced by the Fund’s stock holdings.

• With approximately 60% of its assets allocated to stocks, the Fund is proportionately subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target stock index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• With approximately 40% of its assets allocated to bonds, the Fund is proportionately subject to bond risks, including interest rate risk, which is the chance that bond prices will decline because of rising interest rates; income risk, which is the chance that the Fund’s income will decline because of falling interest rates; credit risk, which is the chance that a bond issuer will fail to pay interest or principal in a timely manner or that negative perceptions of the issuer’s ability to make such payments will cause the price of that bond to decline; and call risk, which is the chance that during periods of falling interest rates, issuers of callable bonds may call (redeem) securities with higher coupon rates or interest rates before their maturity dates. The Fund would then lose any price appreciation above the bond’s call price and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such redemptions and subsequent reinvestments would also increase the Fund’s portfolio turnover rate.

• The Fund is also subject to index sampling risk, which is the chance that the securities selected for the Fund will not provide investment performance matching that of the Fund’s target indexes.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

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Annual Total Returns

The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Investor Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the share classes presented compare with those of relevant market indexes and other comparative indexes, which have investment characteristics similar to those of the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.

Annual Total Returns — Vanguard Balanced Index Fund Investor Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 11.26% (quarter ended September 30, 2009), and the lowest return for a quarter was –12.54% (quarter ended December 31, 2008).

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Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are shown only for the Investor Shares and may differ for each share class. After-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

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Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William A. Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the stock portion of the Fund since 2016.

Gerard C. O’Reilly, Principal of Vanguard. He has co-managed the stock portion of the Fund since 2016.

Joshua C. Barrickman, CFA, Principal of Vanguard and head of Vanguard’s Fixed Income Indexing Americas. He has co-managed the bond portion of the Fund since 2013.

Christopher E. Wrazen, CFP, Portfolio Manager at Vanguard. He has co-managed the bond portion of the Fund since 2015.

Purchase and Sale of Fund Shares

You may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The minimum investment amount required to open and maintain a Fund account for Investor Shares or Admiral Shares is $3,000 or $10,000, respectively. The minimum investment amount required to add to an existing Fund account is generally $1. Institutional, financial intermediary, and Vanguard retail managed clients should contact Vanguard for information on special eligibility rules that may apply to them regarding Admiral Shares. If you are investing through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how to participate in your plan.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply.

Payments to Financial Intermediaries

The Fund and its investment advisor do not pay financial intermediaries for sales of Fund shares.

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Investing in Index Funds

What Is Indexing?

Indexing is an investment strategy for tracking the performance of a specified market benchmark, or “index.” An index is a group of securities whose overall performance is used as a standard to measure the investment performance of a particular market. There are many types of indexes. Some represent entire markets—such as the U.S. stock market or the U.S. bond market. Other indexes cover market segments—such as small-capitalization stocks or short-term bonds. The index sponsor determines the securities to include in the index, the weighting of each security in the index, and the appropriate time to make changes to the composition of the index. One cannot invest directly in an index.

An index fund holds all, or a representative sample, of the securities that make up its target index. Index funds attempt to mirror the performance of the target index, for better or worse. However, an index fund generally does not perform exactly like its target index. For example, like all mutual funds, index funds have operating expenses and transaction costs. Market indexes do not, and therefore they will usually have a slight performance advantage over funds that track them.

Index funds typically have the following characteristics:

• Variety of investments. Most Vanguard index funds generally invest in the securities of a variety of companies and industries.

• Relative performance consistency. Because they seek to track market benchmarks, index funds usually do not perform dramatically better or worse than their benchmarks.

• Low cost. Index funds are inexpensive to run compared with actively managed funds.

They have low or no research costs and typically keep trading activity—and thus brokerage commissions, dealer markups, and other transaction costs—to a minimum compared with actively managed funds.

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More on the Fund

This prospectus describes the principal risks you would face as a Fund shareholder. It is important to keep in mind one of the main axioms of investing: generally, the higher the risk of losing money, the higher the potential reward. The reverse, also, is generally true: the lower the risk, the lower the potential reward. As you consider an investment in any mutual fund, you should take into account your personal tolerance

for fluctuations in the securities markets. Look for this symbol throughout the prospectus. It is used to mark detailed information about the more significant risks that you would confront as a Fund shareholder. To highlight terms and concepts important to mutual fund investors, we have provided Plain Talk^® explanations along the way. Reading the prospectus will help you decide whether the Fund is the right investment for you. We suggest that you keep this prospectus for future reference.

Share Class Overview

This prospectus offers the Fund’s Investor Shares and Admiral Shares. Another prospectus offers the Fund’s Institutional Shares, which are generally for investors who invest a minimum of $5 million.

All share classes offered by the Fund have the same investment objective, strategies, and policies. However, different share classes have different expenses; as a result, their investment performances will differ.

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The following sections explain the principal investment strategies and policies that the Fund uses in pursuit of its objective. The Fund‘s board of trustees, which oversees the Fund’s management, may change investment strategies or policies in the interest of shareholders without a shareholder vote, unless those strategies or policies are designated as fundamental. Note that the Fund’s investment objective is not fundamental and may be changed without a shareholder vote.

Market Exposure

Stocks

Approximately 60% of the Fund’s assets are invested in stocks.

The Fund is subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target stock index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

To illustrate the volatility of stock prices, the following table shows the best, worst, and average annual total returns for the U.S. stock market over various periods as measured by the S&P 500 Index, a widely used barometer of U.S. stock market activity. Total returns consist of dividend income plus change in market price.

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Note that the returns shown do not include the costs of buying and selling stocks or other expenses that a real-world investment portfolio would incur.

The table covers all of the rolling 1-, 5-, 10-, and 20-year periods from 1926 through 2016. You can see, for example, that although the average annual return on common stocks for all of the 5-year periods was 10.1%, average annual returns for individual 5-year periods ranged from –12.4% (from 1928 through 1932) to 28.6% (from 1995 through 1999). These average annual returns reflect past performance of common stocks; you should not regard them as an indication of future performance of either the stock market as a whole or the Fund in particular.

Although the Fund will include a broadly diversified collection of stocks in the CRSP US Total Market Index, it will not include all of the securities in the Index. Instead, the Fund will invest in a representative sample of stocks.

Stocks of publicly traded companies and funds that invest in stocks are often classified according to market value, or market capitalization. These classifications typically include small-cap, mid-cap, and large-cap. It is important to understand that market capitalization ranges change over time. Also, interpretations of size vary, and there are no “official” definitions of small-, mid-, and large-cap, even among Vanguard fund advisors. The asset-weighted median market capitalization of the Fund’s stock holdings as of December 31, 2016, was $54.1 billion.

Although the CRSP US Total Market Index is dominated by large-cap stocks (those tracked by the S&P 500 Index), mid-, small-, and micro-cap stocks are also represented. As of December 31, 2016, approximately 17% of the market value of the CRSP US Total Market Index was made up of securities that were not in the S&P 500 Index. Historically, mid-, small-, and micro-cap stocks have been more volatile than—and at times have performed quite differently from—large-cap stocks.

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Bonds

Approximately 40% of the Fund’s assets are invested in bonds.

The Fund is subject to interest rate risk, which is the chance that bond prices will decline because of rising interest rates. Interest rate risk should be moderate for the Fund because the Fund invests only a portion of its assets in bonds and because the average term of the Fund’s bond portfolio is generally intermediate-term. The prices of intermediate-term bonds are less sensitive to interest rate changes than are the prices of long-term bonds.

Although bonds are often thought to be less risky than stocks, there have been periods when bond prices have fallen significantly because of rising interest rates. For instance, prices of long-term bonds fell by almost 48% between December 1976 and September 1981.

To illustrate the relationship between bond prices and interest rates, the following table shows the effect of a 1% and a 2% change (both up and down) in interest rates on the values of three noncallable bonds (i.e., bonds that cannot be redeemed by the issuer) of different maturities, each with a face value of $1,000.

These figures are for illustration only; you should not regard them as an indication of future performance of the bond market as a whole or the Fund in particular.

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Changes in interest rates can affect bond income as well as bond prices.

The Fund is subject to income risk, which is the chance that the Fund’s income will decline because of falling interest rates. A fund holding bonds will experience a decline in income when interest rates fall because the fund then must invest new cash flow and cash from maturing bonds in lower-yielding bonds.

Although income risk for short- and intermediate-term bonds—like those held by the Fund—is considered moderate, this risk should be low for the Fund because it invests only a portion of its assets in bonds.

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The Fund is subject to credit risk, which is the chance that a bond issuer will fail to pay interest or principal in a timely manner or that negative perceptions of the issuer’s ability to make such payments will cause the price of that bond to decline.

Credit risk should be low for the Fund because it purchases only bonds that are of investment-grade quality.

The Fund is subject to call risk, which is the chance that during periods of falling interest rates, issuers of callable bonds may call (redeem) securities with higher coupon rates or interest rates before their maturity dates. The Fund would then lose any price appreciation above the bond’s call price and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such redemptions and subsequent reinvestments would also increase the Fund’s portfolio turnover rate.

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The Fund is also subject to prepayment risk, which is the chance that during periods of falling interest rates, homeowners will refinance their mortgages before their maturity dates, resulting in prepayment of mortgage-backed securities held by the Fund. The Fund would then lose any price appreciation above the mortgage’s principal and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such prepayments and subsequent reinvestments would also increase the Fund’s portfolio turnover rate. Because the Fund invests only a portion of its assets in callable bonds and mortgage-backed securities, call risk and prepayment risk for the Fund should be low.

The Fund is subject to extension risk. Extension risk is the chance that during periods of rising interest rates, certain debt securities will be paid off substantially more slowly than originally anticipated, and the value of those securities may fall. For funds that invest in mortgage-backed securities, extension risk is the chance that during periods of rising interest rates, homeowners will prepay their mortgages at slower rates. Extension risk should be low for the Fund because it invests only a portion of its assets in bonds.

To a limited extent, the Fund is also exposed to event risk, which is the chance that corporate fixed income securities held by the Fund may suffer a substantial decline in credit quality and market value because of a corporate restructuring or another corporate event.

The Fund’s bond holdings may help to reduce—but not eliminate—some of the stock market volatility that may be experienced by the Fund. Likewise, changes in interest rates may not have as dramatic an effect on the Fund as they would on a fund made up entirely of bonds. The Fund’s balanced portfolio, in the long run, should result in less investment risk—and a lower investment return—than a fund investing exclusively in common stocks.

Security Selection

Index sampling strategy. Because it would be very expensive and inefficient to buy and sell all the securities held in its target indexes, the Fund uses an index “sampling” technique to select securities. Using computer programs, the Fund generally selects a representative sample of securities that approximates the full target indexes in terms of key risk factors and other characteristics. In its stock portion, the Fund holds a broadly diversified collection of stocks that approximates the CRSP US Total Market Index in terms of factors such as industry weightings, market capitalization, and other financial characteristics of stocks. In its bond portion, the Fund considers factors such as duration, cash flow, quality, and callability of the underlying bonds when sampling the Bloomberg Barclays U.S. Aggregate Float Adjusted Index. In addition, the Fund’s bond portion keeps industry sector and subsector exposure within tight boundaries compared with that of the Index.

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Because the Fund does not hold all the securities in its target indexes, some of the securities (and issuers) that are held will likely be overweighted compared with the target indexes.

The Fund is subject to index sampling risk, which is the chance that the securities selected for the Fund will not provide investment performance matching that of the Fund’s target indexes.

Types of bonds. The Fund’s target index for bonds, the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, represents a wide spectrum of investment-grade fixed income securities in the United States—including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed and asset-backed securities—all with maturities of more than 1 year.

As of December 31, 2016, the Fund’s bond portion was made up of the following types of bonds:

An explanation of each type of bond follows:

• U.S. government and agency bonds represent loans by investors to the U.S.

Treasury or a wide variety of government agencies and instrumentalities. Timely payment of principal and interest on U.S. Treasury bonds is always guaranteed by the full faith and credit of the U.S. government; many (but not all) agency bonds have the same guarantee. The market values of U.S. government and agency securities and

U.S. Treasury securities are subject to fluctuation.

• Corporate bonds are IOUs issued by businesses that want to borrow money for

some purpose—often to develop a new product or service, to expand into a new market, or to buy another company. As with other types of bonds, the issuer promises to repay the principal on a specific date and to make interest payments in the meantime. The amount of interest offered depends both on market conditions and on the financial health of the corporation issuing the bonds; a company whose credit rating is not strong will have to offer a higher interest rate to obtain buyers for its bonds. Corporate bonds include securities that are backed by a pool of underlying assets (asset-backed securities) or commercial mortgages (commercial mortgage-backed bonds). The Fund expects to purchase only investment-grade corporate bonds.

• Mortgage-backed securities represent interests in underlying pools of mortgages.

Unlike ordinary bonds, which generally pay a fixed rate of interest at regular intervals and then repay principal upon maturity, mortgage-backed securities pass through both

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interest and principal from underlying mortgages as part of their regular payments. Because the mortgages underlying the securities can be prepaid at any time by homeowners or corporate borrowers, mortgage-backed securities are subject to prepayment risk. These types of securities are issued by a number of government agencies, including the Government National Mortgage Association (GNMA), the Federal Home Loan Mortgage Corporation (FHLMC), and the Federal National Mortgage Association (FNMA). GNMAs are guaranteed by the full faith and credit of the U.S. government as to the timely payment of principal and interest; mortgage-backed securities issued by other government agencies or private corporations are not.

The Fund may also invest in conventional mortgage-backed securities—which are packaged by private corporations and are not guaranteed by the U.S. government—and enter into mortgage-dollar-roll transactions. In a mortgage-dollar-roll transaction, a fund sells mortgage-backed securities to a dealer and simultaneously agrees to purchase similar securities in the future at a predetermined price. These transactions simulate an investment in mortgage-backed securities and have the potential to enhance the Fund’s returns and reduce its administrative burdens, compared with holding mortgage-backed securities directly. These transactions may increase a fund’s portfolio turnover rate. Mortgage dollar rolls will be used only if consistent with the Fund’s investment objective and risk profile.

• International dollar-denominated bonds are bonds denominated in U.S. dollars and issued by foreign governments and companies. To the extent that it owns foreign bonds, the Fund is subject to country risk, which is the chance that world events—such as political upheaval, financial troubles, or natural disasters—will adversely affect the value and/or liquidity of securities issued by companies in foreign countries. Because the bond’s value is designated in dollars rather than in the currency of the issuer’s country, the investor is not exposed to currency risk; rather, the issuer assumes the risk, usually to attract U.S. investors.

Other Investment Policies and Risks

The Fund reserves the right to substitute a different index for either of the indexes that it currently tracks if a current index is discontinued, if the Fund’s agreement with the sponsor of a current index is terminated, or for any other reason determined in good faith by the Fund’s board of trustees. In any such instance, the substitute index would represent the same market segment as the current index.

The Fund may invest in foreign stocks to the extent necessary to carry out its investment strategy of holding a representative sample of the stocks that make up the index it tracks. It is not expected that the Fund will invest more than 5% of its assets in foreign stocks.

Up to 20% of the bond portion of the Fund may be used to purchase nonpublic, investment-grade securities, generally referred to as 144A securities, as well as

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smaller public issues or medium-term notes not included in the Bloomberg Barclays U.S. Aggregate Float Adjusted Index because of the size of the issue. Subject to the same 20% limit, the Fund also may invest in relatively conservative classes of collateralized mortgage obligations (CMOs), which offer a high degree of cash-flow predictability and a low level of vulnerability to mortgage prepayment risk. To reduce credit risk, these CMOs are purchased only if issued by agencies of the U.S. government or by private companies that carry high-quality investment-grade ratings. The vast majority of any such securities will have characteristics and risks similar to those in the Index.

The Fund may invest, to a limited extent, in derivatives. Generally speaking, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, a bond, or a currency), a physical asset (such as gold, oil, or wheat), a market index (such as the S&P 500 Index), or a reference rate (such as LIBOR). Investments in derivatives may subject the Fund to risks different from, and possibly greater than, those of investments directly in the underlying securities or assets. The Fund will not use derivatives for speculation or for the purpose of leveraging (magnifying) investment returns.

The Fund may purchase money market instruments and certain derivatives in order to manage cash flow into and out of the Fund, reduce the Fund’s transaction costs, or add value when these instruments are favorably priced.

The Fund may invest a small portion of its assets in equity futures and fixed income futures, which are types of derivatives, and/or shares of stock and bond exchange-traded funds (ETFs). These futures and ETFs typically provide returns similar to those of the stocks and bonds listed in the index, or in a subset of the index, tracked by the Fund. The Fund may purchase futures or ETFs when doing so will reduce the Fund’s transaction costs, facilitate cash management, mitigate risk, or have the potential to add value because the instruments are favorably priced. Vanguard receives no additional revenue from Fund assets invested in ETF Shares of other Vanguard funds. Fund assets invested in ETF Shares are excluded when allocating to the Fund its share of the costs of Vanguard operations.

Cash Management

The Fund‘s daily cash balance may be invested in one or more Vanguard CMT Funds, which are very low-cost money market funds. When investing in a Vanguard CMT Fund, the Fund bears its proportionate share of the expenses of the CMT Fund in which it invests. Vanguard receives no additional revenue from Fund assets invested in a Vanguard CMT Fund.

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Temporary Investment Measures

The Fund may temporarily depart from its normal investment policies and strategies when the advisor believes that doing so is in the Fund‘s best interest, so long as the alternative is consistent with the Fund‘s investment objective. For instance, the Fund may invest beyond its normal limits in derivatives or exchange-traded funds that are consistent with the Fund‘s objective when those instruments are more favorably priced or provide needed liquidity, as might be the case when the Fund receives large cash flows that it cannot prudently invest immediately.

Frequent Trading or Market-Timing

Background. Some investors try to profit from strategies involving frequent trading of mutual fund shares, such as market-timing. For funds holding foreign securities, investors may try to take advantage of an anticipated difference between the price of the fund’s shares and price movements in overseas markets, a practice also known as time-zone arbitrage. Investors also may try to engage in frequent trading of funds holding investments such as small-cap stocks and high-yield bonds. As money is shifted into and out of a fund by a shareholder engaging in frequent trading, the fund incurs costs for buying and selling securities, resulting in increased brokerage and administrative costs. These costs are borne by all fund shareholders, including the long-term investors who do not generate the costs. In addition, frequent trading may interfere with an advisor’s ability to efficiently manage the fund.

Policies to address frequent trading. The Vanguard funds (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) do not knowingly accommodate frequent trading. The board of trustees of each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) has adopted policies and procedures reasonably designed to detect and discourage frequent trading and, in some cases, to compensate the fund for the costs associated with it. These policies and procedures do not apply to Vanguard ETF^® Shares because frequent trading in ETF Shares generally does not disrupt portfolio management or otherwise harm fund shareholders. Although there is no assurance that Vanguard will be able to detect or prevent frequent trading or market-timing in all circumstances, the following policies have been adopted to address these issues:

• Each Vanguard fund reserves the right to reject any purchase request—including exchanges from other Vanguard funds—without notice and regardless of size. For example, a purchase request could be rejected because the investor has a history of frequent trading or if Vanguard determines that such purchase may negatively affect a fund’s operation or performance.

• Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) generally prohibits, except as otherwise noted in the Investing With Vanguard section, an

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investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account.

• Certain Vanguard funds charge shareholders purchase and/or redemption fees on transactions.

See the Investing With Vanguard section of this prospectus for further details on Vanguard’s transaction policies.

Each Vanguard fund (other than retail and government money market funds), in determining its net asset value, will use fair-value pricing when appropriate, as described in the Share Price section. Fair-value pricing may reduce or eliminate the profitability of certain frequent-trading strategies.

Do not invest with Vanguard if you are a market-timer.

Turnover Rate

Although the Fund generally seeks to invest for the long term, it may sell securities regardless of how long they have been held. Generally, an index fund sells securities in response to redemption requests or to changes in the composition of its target index or in an effort to manage the fund’s duration. The Financial Highlights section of this prospectus shows historical turnover rates for the Fund. A turnover rate of 100%, for example, would mean that the Fund had sold and replaced securities valued at 100% of its net assets within a one-year period.

The Fund and Vanguard

The Fund is a member of The Vanguard Group, a family of more than 190 mutual funds holding assets of approximately $3.6 trillion. All of the funds that are members of The Vanguard Group (other than funds of funds) share in the expenses associated with administrative services and business operations, such as personnel, office space, and equipment.

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Vanguard Marketing Corporation provides marketing services to the funds. Although shareholders do not pay sales commissions or 12b-1 distribution fees, each fund (other than a fund of funds) or each share class of a fund (in the case of a fund with multiple share classes) pays its allocated share of the Vanguard funds’ marketing costs.

Investment Advisor

The Vanguard Group, Inc. (Vanguard), P.O. Box 2600, Valley Forge, PA 19482, which began operations in 1975, serves as advisor to the Fund through its Equity Index and Fixed Income Groups. As of December 31, 2016, Vanguard served as advisor for approximately $3.1 trillion in assets. Vanguard provides investment advisory services to the Fund on an at-cost basis, subject to the supervision and oversight of the trustees and officers of the Fund.

For the fiscal year ended December 31, 2016, the advisory expenses represented an effective annual rate of 0.01% of the Fund’s average net assets.

For a discussion of why the board of trustees approved the Fund’s investment advisory arrangement, see the most recent semiannual report to shareholders covering the fiscal period ended June 30.

The managers primarily responsible for the day-to-day management of the Fund are:

William A. Coleman, CFA, Portfolio Manager at Vanguard. He has worked in investment management since joining Vanguard in 2006 and has co-managed the stock portion of the Fund since 2016. Education: B.S., King’s College; M.S., Saint Joseph’s University.

Gerard C. O’Reilly, Principal of Vanguard. He has been with Vanguard since 1992, has managed investment portfolios since 1994, and has co-managed the stock portion of the Fund since 2016. Education: B.S., Villanova University.

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Joshua C. Barrickman, CFA, Principal of Vanguard and head of Vanguard’s Fixed Income Indexing Americas. He has been with Vanguard since 1998, has worked in investment management since 1999, has managed investment portfolios since 2005, and has co-managed the bond portion of the Fund since 2013. Education: B.S., Ohio Northern University; M.B.A., Lehigh University.

Christopher E. Wrazen, CFP, Portfolio Manager at Vanguard. He has been with Vanguard since 2004, has worked in investment management since 2008, has managed investment portfolios since 2015, and has co-managed the bond portion of the Fund since 2015. Education: B.S., West Chester University; M.B.A., Drexel University.

The Statement of Additional Information provides information about each portfolio manager’s compensation, other accounts under management, and ownership of shares of the Fund.

Dividends, Capital Gains, and Taxes

Fund Distributions

The Fund distributes to shareholders virtually all of its net income (interest and dividends, less expenses) as well as any net short-term or long-term capital gains realized from the sale of its holdings. Income dividends generally are distributed quarterly in March, June, September, and December; capital gains distributions, if any, generally occur annually in December. In addition, the Fund may occasionally make a supplemental distribution at some other time during the year.

You can receive distributions of income or capital gains in cash, or you can have them automatically reinvested in more shares of the Fund. However, if you are investing through an employer-sponsored retirement or savings plan, your distributions will be automatically reinvested in additional Fund shares.

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Basic Tax Points

Investors in taxable accounts should be aware of the following basic federal income tax points:

• Distributions are taxable to you whether or not you reinvest these amounts in additional Fund shares.

• Distributions declared in December—if paid to you by the end of January—are taxable as if received in December.

• Any dividend distribution or short-term capital gains distribution that you receive is taxable to you as ordinary income. If you are an individual and meet certain holding-period requirements with respect to your Fund shares, you may be eligible for reduced tax rates on “qualified dividend income,” if any, distributed by the Fund.

• Any distribution of net long-term capital gains is taxable to you as long-term capital gains, no matter how long you have owned shares in the Fund.

• Capital gains distributions may vary considerably from year to year as a result of the Fund‘s normal investment activities and cash flows.

• A sale or exchange of Fund shares is a taxable event. This means that you may have a capital gain to report as income, or a capital loss to report as a deduction, when you complete your tax return.

• Any conversion between classes of shares of the same fund is a nontaxable event. By contrast, an exchange between classes of shares of different funds is a taxable event.

• Vanguard (or your intermediary) will send you a statement each year showing the tax status of all of your distributions.

Individuals, trusts, and estates whose income exceeds certain threshold amounts are subject to a 3.8% Medicare contribution tax on “net investment income.” Net investment income takes into account distributions paid by the Fund and capital gains from any sale or exchange of Fund shares.

Dividend distributions and capital gains distributions that you receive, as well as your gains or losses from any sale or exchange of Fund shares, may be subject to state and local income taxes.

This prospectus provides general tax information only. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. Please consult your tax advisor for detailed information about any tax consequences for you.

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General Information

Backup withholding. By law, Vanguard must withhold 28% of any taxable distributions or redemptions from your account if you do not:

• Provide your correct taxpayer identification number.
• Certify that the taxpayer identification number is correct.
• Confirm that you are not subject to backup withholding.

Similarly, Vanguard (or your intermediary) must withhold taxes from your account if the IRS instructs us to do so.

Foreign investors. Vanguard funds offered for sale in the United States (Vanguard U.S. funds), including the Fund offered in this prospectus, are not widely available outside the United States. Non-U.S. investors should be aware that U.S. withholding and estate taxes and certain U.S. tax reporting requirements may apply to any investments in Vanguard U.S. funds. Foreign investors should visit the Non-U.S. Investors page on our website at vanguard.com for information on Vanguard’s non-U.S. products.

Invalid addresses. If a dividend distribution or capital gains distribution check mailed to your address of record is returned as undeliverable, Vanguard will automatically reinvest the distribution and all future distributions until you provide us with a valid mailing address. Reinvestments will receive the net asset value calculated on the date of the reinvestment.

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Share Price

Share price, also known as net asset value (NAV), is calculated each business day as of the close of regular trading on the New York Stock Exchange (NYSE), generally 4 p.m., Eastern time. Each share class has its own NAV, which is computed by dividing the total assets, minus liabilities, allocated to the share class by the number of Fund shares outstanding for that class. On U.S. holidays or other days when the NYSE is closed, the NAV is not calculated, and the Fund does not sell or redeem shares. However, on those days the value of the Fund’s assets may be affected to the extent that the Fund holds securities that change in value on those days (such as foreign securities that trade on foreign markets that are open).

Stocks held by a Vanguard fund are valued at their market value when reliable market quotations are readily available from the principal exchange or market on which they are traded. Such securities are generally valued at their official closing price, the last reported sales price, or if there were no sales that day, the mean between the closing bid and asking prices. Debt securities held by a fund are valued based on information furnished by an independent pricing service or market quotations. When a fund determines that pricing-service information or market quotations either are not readily available or do not accurately reflect the value of a security, the security is priced at its fair value (the amount that the owner might reasonably expect to receive upon the current sale of the security).

The values of any foreign securities held by a fund are converted into U.S. dollars using an exchange rate obtained from an independent third party as of the close of regular trading on the NYSE. The values of any mutual fund shares, including institutional money market fund shares, held by a fund are based on the NAVs of the shares. The values of any ETF shares or closed-end fund shares held by a fund are based on the market value of the shares.

A fund also will use fair-value pricing if the value of a security it holds has been materially affected by events occurring before the fund’s pricing time but after the close of the principal exchange or market on which the security is traded. This most commonly occurs with foreign securities, which may trade on foreign exchanges that close many hours before the fund’s pricing time. Intervening events might be company-specific (e.g., earnings report, merger announcement) or country-specific or regional/global (e.g., natural disaster, economic or political news, act of terrorism, interest rate change). Intervening events include price movements in U.S. markets that exceed a specified threshold or that are otherwise deemed to affect the value of foreign securities.

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Fair-value pricing may be used for domestic securities—for example, if (1) trading in a security is halted and does not resume before the fund’s pricing time or a security does not trade in the course of a day and (2) the fund holds enough of the security that its price could affect the NAV. A fund may use fair-value pricing with respect to its fixed income securities on bond market holidays when the fund is open for business (such as Columbus Day and Veterans Day).

Fair-value prices are determined by Vanguard according to procedures adopted by the board of trustees. When fair-value pricing is employed, the prices of securities used by a fund to calculate the NAV may differ from quoted or published prices for the same securities.

Vanguard fund share prices are published daily on our website at vanguard.com/prices.

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Financial Highlights

The following financial highlights tables are intended to help you understand the Fund’s financial performance for the periods shown, and certain information reflects financial results for a single Fund share. The total returns in each table represent the rate that an investor would have earned or lost each period on an investment in the Fund (assuming reinvestment of all distributions). This information has been obtained from the financial statements audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, whose report—along with the Fund’s financial statements—is included in the Fund‘s most recent annual report to shareholders. You may obtain a free copy of the latest annual or semiannual report by visiting vanguard.com or by contacting Vanguard by telephone or mail.

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Investing With Vanguard

This section of the prospectus explains the basics of doing business with Vanguard. Vanguard fund shares can be held directly with Vanguard or indirectly through an intermediary, such as a bank, a broker, or an investment advisor. If you hold Vanguard fund shares directly with Vanguard, you should carefully read each topic within this section that pertains to your relationship with Vanguard. If you hold Vanguard fund shares indirectly through an intermediary (including shares held through a Vanguard brokerage account), please see Investing With Vanguard Through Other Firms, and also refer to your account agreement with the intermediary for information about transacting in that account. If you hold Vanguard fund shares through an employer-sponsored retirement or savings plan, please see Employer-Sponsored Plans. Vanguard reserves the right to change the following policies without notice. Please call or check online for current information. See Contacting Vanguard.

For Vanguard fund shares held directly with Vanguard, each fund you hold in an account is a separate “fund account.” For example, if you hold three funds in a nonretirement account titled in your own name, two funds in a nonretirement account titled jointly with your spouse, and one fund in an individual retirement account, you have six fund accounts—and this is true even if you hold the same fund in multiple accounts. Note that each reference to “you” in this prospectus applies to any one or more registered account owners or persons authorized to transact on your account.

Purchasing Shares

Vanguard reserves the right, without notice, to increase or decrease the minimum amount required to open, convert shares to, or maintain a fund account or to add to an existing fund account.

Investment minimums may differ for certain categories of investors.

Account Minimums for Investor Shares To open and maintain an account. $3,000.

To add to an existing account. Generally $1.

Account Minimums for Admiral Shares

To open and maintain an account. $10,000. If you request Admiral Shares when you open a new account but the investment amount does not meet the account minimum for Admiral Shares, your investment will be placed in Investor Shares of the Fund. Institutional, financial intermediary, and Vanguard retail managed clients should contact Vanguard for information on special eligibility rules that may apply to them.

To add to an existing account. Generally $1.

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How to Initiate a Purchase Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your purchase request.

Online. You may open certain types of accounts, request a purchase of shares, and request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to begin the account registration process or request that the account-opening forms be sent to you. You may also call Vanguard to request a purchase of shares in your account or to request an exchange. See

Contacting Vanguard.

By mail. You may send Vanguard your account registration form and check to open a new fund account. To add to an existing fund account, you may send your check with an Invest-by-Mail form (from a transaction confirmation or your account statement), with a deposit slip (available online), or with a written request. You may also send a written request to Vanguard to make an exchange. For a list of Vanguard addresses, see Contacting Vanguard.

How to Pay for a Purchase

By electronic bank transfer. You may purchase shares of a Vanguard fund through an electronic transfer of money from a bank account. To establish the electronic bank transfer service on an account, you must designate the bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set up on your account, you can purchase shares by electronic bank transfer on a regular schedule (Automatic Investment Plan) or upon request. Your purchase request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. Wiring instructions vary for different types of purchases. Please call Vanguard for instructions and policies on purchasing shares by wire. See Contacting Vanguard.

By check. You may make initial or additional purchases to your fund account by sending a check or by utilizing our mobile application if you are registered for online access. Also see How to Initiate a Purchase Request. Make your check payable to Vanguard and include the appropriate fund number (e.g., Vanguard—xx). For a list of Fund numbers (for share classes in this prospectus), see Additional Information.

By exchange. You may purchase shares of a Vanguard fund using the proceeds from the simultaneous redemption of shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See

Exchanging Shares.

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Trade Date

The trade date for any purchase request received in good order will depend on the day and time Vanguard receives your request, the manner in which you are paying, and the type of fund you are purchasing. Your purchase will be executed using the net asset value (NAV) as calculated on the trade date. NAVs are calculated only on days that the New York Stock Exchange (NYSE) is open for trading (a business day).

For purchases by check into all funds other than money market funds and for purchases by exchange, wire, or electronic bank transfer (not using an Automatic Investment Plan) into all funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the same day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the next business day.

For purchases by check into money market funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the next business day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the second business day following the day Vanguard receives the purchase request. Because money market instruments must be purchased with federal funds and it takes a money market mutual fund one business day to convert check proceeds into federal funds, the trade date for the purchase will be one business day later than for other funds.

For purchases by electronic bank transfer using an Automatic Investment Plan: Your trade date generally will be the date you selected for withdrawal of funds from your designated bank account. Your bank account generally will be debited on the business day after your trade date. If the date you selected for withdrawal of funds from your bank account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your designated bank account falls on the last business day of the year, your trade date will be the first business day of the following year. Please note that if you select the first of the month for automated withdrawals from your designated bank account, trades designated for January 1 will receive the next business day’s trade date.

If your purchase request is not accurate and complete, it may be rejected. See Other Rules You Should Know—Good Order.

For further information about purchase transactions, consult our website at vanguard.com or see Contacting Vanguard.

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Other Purchase Rules You Should Know

Admiral Shares. Admiral Shares generally are not available for SIMPLE IRAs, Vanguard Individual 401(k) Plans, and Vanguard retail-serviced Individual 403(b)(7) Custodial Accounts.

Check purchases. All purchase checks must be written in U.S. dollars and must be drawn on a U.S. bank. Vanguard does not accept cash, traveler’s checks, or money orders. In addition, Vanguard may refuse “starter checks” and checks that are not made payable to Vanguard.

New accounts. We are required by law to obtain from you certain personal information that we will use to verify your identity. If you do not provide the information, we may not be able to open your account. If we are unable to verify your identity, Vanguard reserves the right, without notice, to close your account or take such other steps as we deem reasonable. Certain types of accounts may require additional documentation.

Refused or rejected purchase requests. Vanguard reserves the right to stop selling fund shares or to reject any purchase request at any time and without notice, including, but not limited to, purchases requested by exchange from another Vanguard fund. This also includes the right to reject any purchase request because the investor has a history of frequent trading or because the purchase may negatively affect a fund’s operation or performance.

Large purchases. Call Vanguard before attempting to invest a large dollar amount.

No cancellations. Vanguard will not accept your request to cancel any purchase request once processing has begun. Please be careful when placing a purchase request.

Converting Shares

When a conversion occurs, you receive shares of one class in place of shares of another class of the same fund. At the time of conversion, the dollar value of the “new” shares you receive equals the dollar value of the “old” shares that were converted. In other words, the conversion has no effect on the value of your investment in the fund at the time of the conversion. However, the number of shares you own after the conversion may be greater than or less than the number of shares you owned before the conversion, depending on the NAVs of the two share classes.

Vanguard will not accept your request to cancel any self-directed conversion request once processing has begun. Please be careful when placing a conversion request.

A conversion between share classes of the same fund is a nontaxable event.

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Trade Date

The trade date for any conversion request received in good order will depend on the day and time Vanguard receives your request. Your conversion will be executed using the NAVs of the different share classes on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

For a conversion request received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. For a conversion request received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day. See Other Rules You Should Know.

Conversions From Investor Shares to Admiral Shares

Self-directed conversions. If your account balance in the Fund is at least $10,000, you may ask Vanguard to convert your Investor Shares to Admiral Shares. You may request a conversion through our website (if you are registered for online access), by telephone, or by mail. Institutional, financial intermediary, and Vanguard retail managed clients should contact Vanguard for information on special eligibility rules that may apply to them. See Contacting Vanguard.

Automatic conversions. Vanguard conducts periodic reviews of account balances and may, if your account balance in the Fund exceeds $10,000, automatically convert your Investor Shares to Admiral Shares. You will be notified before an automatic conversion occurs and will have an opportunity to instruct Vanguard not to effect the conversion. Institutional, financial intermediary, and Vanguard retail managed clients should contact Vanguard for information on special eligibility rules that may apply to them.

Conversions to Institutional Shares

You are eligible for a self-directed conversion from another share class to Institutional Shares of the Fund, provided that your account meets all Institutional Shares’ eligibility requirements. You may request a conversion through our website (if you are registered for online access), or you may contact Vanguard by telephone or by mail to request this transaction. Accounts that qualify for Institutional Shares will not be automatically converted.

Mandatory Conversions to Another Share Class

If an account no longer meets the balance requirements for a share class, Vanguard may automatically convert the shares in the account to another share class, as appropriate. A decline in the account balance because of market movement may result in such a conversion. Vanguard will notify the investor in writing before any mandatory conversion occurs.

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Redeeming Shares

How to Initiate a Redemption Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your redemption request.

Online. You may request a redemption of shares or request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to request a redemption of shares or an exchange. See Contacting Vanguard.

By mail. You may send a written request to Vanguard to redeem from a fund account or to make an exchange. See Contacting Vanguard.

How to Receive Redemption Proceeds

By electronic bank transfer. You may have the proceeds of a fund redemption sent directly to a designated bank account. To establish the electronic bank transfer service on an account, you must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set up on your account, you can redeem shares by electronic bank transfer on a regular schedule (Automatic Withdrawal Plan) or upon request. Your redemption request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. To receive your proceeds by wire, you may instruct Vanguard to wire your redemption proceeds ($100 minimum) to a previously designated bank account. To establish the wire redemption service, you generally must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form.

By exchange. You may have the proceeds of a Vanguard fund redemption invested directly in shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See Exchanging Shares.

By check. If you have not chosen another redemption method, Vanguard will mail you a redemption check, generally payable to all registered account owners, normally within two business days of your trade date, and generally to the address of record.

Trade Date

The trade date for any redemption request received in good order will depend on the day and time Vanguard receives your request and the manner in which you are redeeming. Your redemption will be executed using the NAV as calculated on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

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For redemptions by check, exchange, or wire: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

• Note on timing of wire redemptions from money market funds: For telephone requests received by Vanguard on a business day before 10:45 a.m., Eastern time (2 p.m., Eastern time, for Vanguard Prime Money Market Fund; 12:30 p.m., Eastern time, for Vanguard Federal Money Market Fund), the redemption proceeds generally will leave Vanguard by the close of business the same day. For telephone requests received by Vanguard on a business day after those cut-off times, or on a nonbusiness day, and for all requests other than by telephone, the redemption proceeds generally will leave Vanguard by the close of business on the next business day.

• Note on timing of wire redemptions from all other funds: For requests received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the redemption proceeds generally will leave Vanguard by the close of business on the next business day. For requests received by Vanguard on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the redemption proceeds generally will leave Vanguard by the close of business on the second business day after Vanguard receives the request.

For redemptions by electronic bank transfer using an Automatic Withdrawal Plan: Your trade date generally will be the date you selected for withdrawal of funds (redemption of shares) from your Vanguard account. Proceeds of redeemed shares generally will be credited to your designated bank account two business days after your trade date. If the date you selected for withdrawal of funds from your Vanguard account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your Vanguard account falls on the last day of the year and if that date is a holiday, your trade date will be the first business day of the following year. Please note that if you designate the first of the month for automated withdrawals, trades designated for January 1 will receive the next business day’s trade date.

For redemptions by electronic bank transfer not using an Automatic Withdrawal Plan: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

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If your redemption request is not accurate and complete, it may be rejected. If we are unable to send your redemption proceeds by wire or electronic bank transfer because the receiving institution rejects the transfer, Vanguard will make additional efforts to complete your transaction. If Vanguard is still unable to complete the transaction, we may send the proceeds of the redemption to you by check, generally payable to all registered account owners, or use your proceeds to purchase new shares of the fund from which you sold shares for the purpose of the wire or electronic bank transfer transaction. See Other Rules You Should Know—Good Order.

For further information about redemption transactions, consult our website at vanguard.com or see Contacting Vanguard.

Other Redemption Rules You Should Know

Documentation for certain accounts. Special documentation may be required to redeem from certain types of accounts, such as trust, corporate, nonprofit, or retirement accounts. Please call us before attempting to redeem from these types of accounts.

Potentially disruptive redemptions. Vanguard reserves the right to pay all or part of a redemption in kind—that is, in the form of securities—if we reasonably believe that a cash redemption would negatively affect the fund’s operation or performance or that the shareholder may be engaged in market-timing or frequent trading. Under these circumstances, Vanguard also reserves the right to delay payment of the redemption proceeds for up to seven calendar days. By calling us before you attempt to redeem a large dollar amount, you may avoid in-kind or delayed payment of your redemption. Please see Frequent-Trading Limitations for information about Vanguard’s policies to limit frequent trading.

Recently purchased shares. Although you can redeem shares at any time, proceeds may not be made available to you until the fund collects payment for your purchase. This may take up to seven calendar days for shares purchased by check or by electronic bank transfer. If you have written a check on a fund with checkwriting privileges, that check may be rejected if your fund account does not have a sufficient available balance.

Address change. If you change your address online or by telephone, there may be up to a 14-day restriction on your ability to request check redemptions online and by telephone. You can request a redemption in writing at any time. Confirmations of address changes are sent to both the old and new addresses.

Payment to a different person or address. At your request, we can make your redemption check payable, or wire your redemption proceeds, to a different person or send it to a different address. However, this generally requires the written consent of all registered account owners and may require additional documentation, such as a signature guarantee or a notarized signature. You may obtain a signature guarantee

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from some commercial or savings banks, credit unions, trust companies, or member firms of a U.S. stock exchange.

No cancellations. Vanguard will not accept your request to cancel any redemption request once processing has begun. Please be careful when placing a redemption request.

Emergency circumstances. Vanguard funds can postpone payment of redemption proceeds for up to seven calendar days. In addition, Vanguard funds can suspend redemptions and/or postpone payments of redemption proceeds beyond seven calendar days at times when the NYSE is closed or during emergency circumstances, as determined by the SEC.

Exchanging Shares

An exchange occurs when you use the proceeds from the redemption of shares of one Vanguard fund to simultaneously purchase shares of a different Vanguard fund. You can make exchange requests online (if you are registered for online access), by telephone, or by mail. See Purchasing Shares and Redeeming Shares.

If the NYSE is open for regular trading (generally until 4 p.m., Eastern time, on a business day) at the time an exchange request is received in good order, the trade date generally will be the same day. See Other Rules You Should Know—Good Order for additional information on all transaction requests.

Vanguard will not accept your request to cancel any exchange request once processing has begun. Please be careful when placing an exchange request.

Call Vanguard before attempting to exchange a large dollar amount. By calling us before you attempt to exchange a large dollar amount, you may avoid delayed or rejected transactions.

Please note that Vanguard reserves the right, without notice, to revise or terminate the exchange privilege, limit the amount of any exchange, or reject an exchange, at any time, for any reason. See Frequent-Trading Limitations for additional restrictions on exchanges.

Frequent-Trading Limitations

Because excessive transactions can disrupt management of a fund and increase the fund’s costs for all shareholders, the board of trustees of each Vanguard fund places certain limits on frequent trading in the funds. Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) limits an investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account. ETF Shares are not subject to these frequent-trading limits.

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For Vanguard Retirement Investment Program pooled plans, the limitations apply to exchanges made online or by telephone.

These frequent-trading limitations do not apply to the following:

• Purchases of shares with reinvested dividend or capital gains distributions.

• Transactions through Vanguard’s Automatic Investment Plan, Automatic Exchange Service, Direct Deposit Service, Automatic Withdrawal Plan, Required Minimum ^® Distribution Service, and Vanguard Small Business Online .

^™

• Discretionary transactions through Vanguard Asset Management Services , ^{® ®} Vanguard Personal Advisor Services , and Vanguard Institutional Advisory Services .

• Redemptions of shares to pay fund or account fees.

• Redemptions of shares to remove excess shareholder contributions to certain types of retirement accounts (including, but not limited to, IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans).

• Transaction requests submitted by mail to Vanguard from shareholders who hold their accounts directly with Vanguard or through a Vanguard brokerage account. (Transaction requests submitted by fax, if otherwise permitted, are subject to the limitations.)

• Transfers and reregistrations of shares within the same fund.

• Purchases of shares by asset transfer or direct rollover.

• Conversions of shares from one share class to another in the same fund.

• Checkwriting redemptions.

• Section 529 college savings plans.

• Certain approved institutional portfolios and asset allocation programs, as well as

trades made by funds or trusts managed by Vanguard or its affiliates that invest in other Vanguard funds. (Please note that shareholders of Vanguard’s funds of funds are subject to the limitations.)

For participants in employer-sponsored defined contribution plans,* the frequent-trading limitations do not apply to:

• Purchases of shares with participant payroll or employer contributions or loan repayments.

• Purchases of shares with reinvested dividend or capital gains distributions.

• Distributions, loans, and in-service withdrawals from a plan.

• Redemptions of shares as part of a plan termination or at the direction of the plan

• Transactions executed through the Vanguard Managed Account Program.

• Redemptions of shares to pay fund or account fees.

• Share or asset transfers or rollovers.

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• Reregistrations of shares.
• Conversions of shares from one share class to another in the same fund.
• Exchange requests submitted by written request to Vanguard. (Exchange requests

submitted by fax, if otherwise permitted, are subject to the limitations.)

* The following Vanguard fund accounts are subject to the frequent-trading limitations: SEP-IRAs, SIMPLE IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans.

Accounts Held by Institutions (Other Than Defined Contribution Plans)

Vanguard will systematically monitor for frequent trading in institutional clients’ accounts. If we detect suspicious trading activity, we will investigate and take appropriate action, which may include applying to a client’s accounts the 30-day policy previously described, prohibiting a client’s purchases of fund shares, and/or revoking the client’s exchange privilege.

Accounts Held by Intermediaries

When intermediaries establish accounts in Vanguard funds for the benefit of their clients, we cannot always monitor the trading activity of the individual clients. However, we review trading activity at the intermediary (omnibus) level, and if we detect suspicious activity, we will investigate and take appropriate action. If necessary, Vanguard may prohibit additional purchases of fund shares by an intermediary, including for the benefit of certain of the intermediary’s clients. Intermediaries also may monitor their clients’ trading activities with respect to Vanguard funds.

For those Vanguard funds that charge purchase and/or redemption fees, intermediaries will be asked to assess these fees on client accounts and remit these fees to the funds. The application of purchase and redemption fees and frequent-trading limitations may vary among intermediaries. There are no assurances that Vanguard will successfully identify all intermediaries or that intermediaries will properly assess purchase and redemption fees or administer frequent-trading limitations. If you invest with Vanguard through an intermediary, please read that firm’s materials carefully to learn of any other rules or fees that may apply.

Other Rules You Should Know

Prospectus and Shareholder Report Mailings

When two or more shareholders have the same last name and address, just one summary prospectus (or prospectus) and/or shareholder report may be sent in an attempt to eliminate the unnecessary expense of duplicate mailings. You may request

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individual prospectuses and reports by contacting our Client Services Department in writing, by telephone, or online. See Contacting Vanguard.

Vanguard.com

Registration. If you are a registered user of vanguard.com, you can review your account holdings; buy, sell, or exchange shares of most Vanguard funds; and perform most other transactions through our website. You must register for this service online.

Electronic delivery. Vanguard can deliver your account statements, transaction confirmations, prospectuses, certain tax forms, and shareholder reports electronically. If you are a registered user of vanguard.com, you can consent to the electronic delivery of these documents by logging on and changing your mailing preferences under “Account Maintenance.” You can revoke your electronic consent at any time through our website, and we will begin to send paper copies of these documents within 30 days of receiving your revocation.

Telephone Transactions

Automatic. When we set up your account, we will automatically enable you to do business with us by telephone, unless you instruct us otherwise in writing.

Tele-Account^®. To obtain fund and account information through Vanguard’s automated telephone service, you must first establish a Personal Identification Number (PIN) by calling Tele-Account at 800-662-6273.

Proof of a caller’s authority. We reserve the right to refuse a telephone request if the caller is unable to provide the requested information or if we reasonably believe that the caller is not an individual authorized to act on the account. Before we allow a caller to act on an account, we may request the following information:

• Authorization to act on the account (as the account owner or by legal documentation or other means).

• Account registration and address.
• Fund name and account number, if applicable.
• Other information relating to the caller, the account owner, or the account.

Good Order

We reserve the right to reject any transaction instructions that are not in “good order.” Good order generally means that your instructions:

• Are provided by the person(s) authorized in accordance with Vanguard’s policies and procedures to access the account and request transactions.

• Include the fund name and account number.

• Include the amount of the transaction (stated in dollars, shares, or percentage).

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Written instructions also must generally include:

• An original signature and date from the authorized person(s).

• Signature guarantees or notarized signatures, if required for the type of transaction.

(Call Vanguard for specific requirements.)

• Any supporting documentation that may be required.

Written instructions are acceptable when a Vanguard form is not applicable. The requirements vary among types of accounts and transactions. For more information, consult our website at vanguard.com or see Contacting Vanguard.

Vanguard reserves the right, without notice, to revise the requirements for good order

Future Trade-Date Requests

Vanguard does not accept requests to hold a purchase, conversion, redemption, or exchange transaction for a future date. All such requests will receive trade dates as previously described in Purchasing Shares, Converting Shares, Redeeming Shares, and

Exchanging Shares. Vanguard reserves the right to return future-dated purchase checks.

Accounts With More Than One Owner

If an account has more than one owner or authorized person, Vanguard generally will accept instructions from any one owner or authorized person.

Responsibility for Fraud

Vanguard will not be responsible for any account losses because of fraud if we reasonably believe that the person transacting business on an account is authorized to do so. Please take precautions to protect yourself from fraud. Keep your account information private, and immediately review any account statements or other information that we provide to you. It is important that you contact Vanguard immediately about any transactions or changes to your account that you believe to be unauthorized.

Uncashed Checks

Please cash your distribution or redemption checks promptly. Vanguard will not pay interest on uncashed checks. Vanguard may be required to transfer assets related to uncashed checks to a state under the state’s abandoned property law.

Dormant Accounts

If your account has no activity in it for a period of time, Vanguard may be required to transfer it to a state under the state’s abandoned property law.

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Unusual Circumstances

If you experience difficulty contacting Vanguard online or by telephone, you can send us your transaction request by regular or express mail. See Contacting Vanguard for addresses.

Investing With Vanguard Through Other Firms

You may purchase or sell shares of most Vanguard funds through a financial intermediary, such as a bank, a broker, or an investment advisor. Please consult your financial intermediary to determine which, if any, shares are available through that firm and to learn about other rules that may apply. Your financial intermediary can provide you with account information and any required tax forms.

Please see Frequent-Trading Limitations—Accounts Held by Intermediaries for information about the assessment of any purchase or redemption fees and the monitoring of frequent trading for accounts held by intermediaries.

Account Service Fee

Vanguard charges a $20 account service fee on fund accounts that have a balance below $10,000 for any reason, including market fluctuation. The account service fee applies to both retirement and nonretirement fund accounts and will be assessed on fund accounts in all Vanguard funds, regardless of the account minimum. The fee, which will be collected by redeeming fund shares in the amount of $20, will be deducted from a fund account only once per calendar year.

If you register on vanguard.com and elect to receive electronic delivery of statements, reports, and other materials for all of your fund accounts, the account service fee for balances below $10,000 will not be charged, so long as that election remains in effect.

The account service fee also does not apply to the following:

• Money market sweep accounts owned in connection with a Vanguard Brokerage Services^® account.

• Accounts held through intermediaries.
• Accounts held by institutional clients.
• Accounts held by Voyager, Voyager Select, Flagship, and Flagship Select clients.

Eligibility is based on total household assets held at Vanguard, with a minimum of $50,000 to qualify for Vanguard Voyager Services^®, $500,000 for Vanguard Voyager Select Services^®, $1 million for Vanguard Flagship Services^®, and $5 million for Vanguard Flagship Select Services^™. Vanguard determines eligibility by aggregating assets of all qualifying accounts held by the investor and immediate family members who reside at the same address. Aggregate assets include investments in Vanguard mutual funds, Vanguard ETFs^®, certain annuities through Vanguard, the Vanguard 529 Plan, and certain small-business accounts. Assets in employer-sponsored retirement plans for which Vanguard provides recordkeeping services may be included in

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determining eligibility if the investor also has a personal account holding Vanguard mutual funds. Note that assets held in a Vanguard Brokerage Services account (other than Vanguard funds, including Vanguard ETFs) are not included when determining a household’s eligibility.

• Participant accounts in employer-sponsored defined contribution plans.* Please consult your enrollment materials for the rules that apply to your account.

• Section 529 college savings plans.

* The following Vanguard fund accounts have alternative fee structures: SIMPLE IRAs,

certain Individual 403(b)(7) Custodial Accounts, Vanguard Retirement Investment Program pooled plans, and Vanguard Individual 401(k) Plans.

Low-Balance Accounts

The Fund reserves the right to liquidate a fund account whose balance falls below the account minimum for any reason, including market fluctuation. This liquidation policy applies to nonretirement fund accounts and accounts that are held through intermediaries. Any such liquidation will be preceded by written notice to the investor.

Right to Change Policies

In addition to the rights expressly stated elsewhere in this prospectus, Vanguard reserves the right, without notice, to (1) alter, add, or discontinue any conditions of purchase (including eligibility requirements), redemption, exchange, conversion, service, or privilege at any time; (2) accept initial purchases by telephone; (3) freeze any account and/or suspend account services if Vanguard has received reasonable notice of a dispute regarding the assets in an account, including notice of a dispute between the registered or beneficial account owners, or if Vanguard reasonably believes a fraudulent transaction may occur or has occurred; (4) temporarily freeze any account and/or suspend account services upon initial notification to Vanguard of the death of the shareholder until Vanguard receives required documentation in good order; (5) alter, impose, discontinue, or waive any purchase fee, redemption fee, account service fee, or other fees charged to a shareholder or a group of shareholders; and (6) redeem an account or suspend account privileges, without the owner’s permission to do so, in cases of threatening conduct or activity Vanguard believes to be suspicious, fraudulent, or illegal. Changes may affect any or all investors. These actions will be taken when, at the sole discretion of Vanguard management, Vanguard reasonably believes they are in the best interest of a fund.

Share Classes

Vanguard reserves the right, without notice, to change the eligibility requirements of its share classes, including the types of clients who are eligible to purchase each share class.

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Fund and Account Updates

Confirmation Statements

We will send (or provide through our website, whichever you prefer) a confirmation of your trade date and the amount of your transaction when you buy, sell, exchange, or convert shares. However, we will not send confirmations reflecting only checkwriting redemptions or the reinvestment of dividend or capital gains distributions. For any month in which you had a checkwriting redemption, a Checkwriting Activity Statement will be sent to you itemizing the checkwriting redemptions for that month. Promptly review each confirmation statement that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on a confirmation statement, or Vanguard will consider the transaction properly processed.

Portfolio Summaries

We will send (or provide through our website, whichever you prefer) quarterly portfolio summaries to help you keep track of your accounts throughout the year. If you prefer, you may request to receive monthly portfolio summaries. Each summary shows the market value of your account at the close of the statement period, as well as all distributions, purchases, redemptions, exchanges, transfers, and conversions for the current calendar quarter (or month). Promptly review each summary that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on the summary, or Vanguard will consider the transaction properly processed.

Tax Information Statements

For most accounts, Vanguard (or your intermediary) is required to provide annual tax forms to assist you in preparing your income tax returns. These forms are generally available for each calendar year early in the following year. Registered users of vanguard.com can also view certain forms through our website. Vanguard (or your intermediary) may also provide you with additional tax-related documentation. For more information, consult our website at vanguard.com or see Contacting Vanguard.

Annual and Semiannual Reports

We will send (or provide through our website, whichever you prefer) reports about Vanguard Balanced Index Fund twice a year, in February and August. These reports include overviews of the financial markets and provide the following specific Fund information:

• Performance assessments and comparisons with industry benchmarks.

• Financial statements with listings of Fund holdings.

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Portfolio Holdings

Please consult the Fund‘s Statement of Additional Information or our website for a description of the policies and procedures that govern disclosure of the Fund’s portfolio holdings.

Employer-Sponsored Plans

Your plan administrator or your employee benefits office can provide you with detailed information on how to participate in your plan and how to elect the Fund as an investment option.

• If you have any questions about the Fund or Vanguard, including those about the Fund’s investment objective, strategies, or risks, contact Vanguard Participant Services toll-free at 800-523-1188 or visit our website at vanguard.com.

• If you have questions about your account, contact your plan administrator or the organization that provides recordkeeping services for your plan.

• Be sure to carefully read each topic that pertains to your transactions with Vanguard.

Vanguard reserves the right to change its policies without notice to shareholders.

Transactions

Processing times for your transaction requests may differ among recordkeepers or among transaction and funding types. Your plan’s recordkeeper (which may also be Vanguard) will determine the necessary processing time frames for your transaction requests prior to submission to the Fund. Consult your recordkeeper or plan administrator for more information.

If Vanguard is serving as your plan recordkeeper and if your transaction involves one or more investments with an early cut-off time for processing or another trading restriction, your entire transaction will be subject to the restriction when the trade date for your transaction is determined.

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Vanguard Addresses

Please be sure to use the correct address. Use of an incorrect address could delay the processing of your transaction.

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CFA^® is a registered trademark owned by CFA Institute.

Vanguard funds are not sponsored, endorsed, sold, or promoted by the University of Chicago or its Center for Research in Security Prices, and neither the University of Chicago nor its Center for Research in Security Prices makes any representation regarding the advisability of investing in the funds.

Vanguard Balanced Index Fund is not sponsored, endorsed, issued, sold or promoted by Barclays Risk Analytics and Index Solutions Limited or any of its affiliates (“Barclays”). Barclays makes no representation or warranty, express or implied, to the owners or purchasers of Vanguard Balanced Index Fund or any member of the public regarding the advisability of investing in securities generally or in Vanguard Balanced Index Fund particularly or the ability of the Barclays Index to track general bond market performance. Barclays has not passed on the legality or suitability of the Vanguard Balanced Index Fund with respect to any person or entity. Barclays’ only relationship to Vanguard and Vanguard Balanced Index Fund is the licensing of the Barclays Index which is determined, composed and calculated by Barclays without regard to Vanguard or the Vanguard Balanced Index Fund or any owners or purchasers of the Vanguard Balanced Index Fund. Barclays has no obligation to take the needs of Vanguard, Vanguard Balanced Index Fund or the owners of Vanguard Balanced Index Fund into consideration in determining, composing or calculating the Barclays Index. Barclays is not responsible for and has not participated in the determination of the timing of, prices at, or quantities of Vanguard Balanced Index Fund to be issued. Barclays has no obligation or liability in connection with the administration, marketing or trading of the Vanguard Balanced Index Fund.

BARCLAYS SHALL HAVE NO LIABILITY TO THIRD PARTIES FOR THE QUALITY, ACCURACY AND/OR COMPLETENESS OF THE INDEX OR ANY DATA INCLUDED THEREIN OR FOR INTERRUPTIONS IN THE DELIVERY OF THE INDEX. BARCLAYS MAKES NO WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY OWNERS OF THE VANGUARD BALANCED INDEX FUND OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDEX OR ANY DATA INCLUDED THEREIN IN CONNECTION WITH THE RIGHTS LICENSED HEREUNDER OR FOR ANY OTHER USE. BARCLAYS RESERVES THE RIGHT TO CHANGE THE METHODS OF CALCULATION OR PUBLICATION, OR TO CEASE THE CALCULATION OR PUBLICATION OF THE BLOOMBERG BARCLAYS U.S. AGGREGATE FLOAT ADJUSTED INDEX, AND BARCLAYS SHALL NOT BE LIABLE FOR ANY MISCALCULATION OF OR ANY INCORRECT, DELAYED OR INTERRUPTED PUBLICATION WITH RESPECT TO ANY OF THE BLOOMBERG BARCLAYS U.S. AGGREGATE FLOAT ADJUSTED INDEX. BARCLAYS MAKES NO EXPRESS OR IMPLIED WARRANTIES, AND HEREBY EXPRESSLY DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE WITH RESPECT TO THE INDEX OR ANY DATA INCLUDED THEREIN. BARCLAYS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING, WITHOUT LIMITATION, ANY INDIRECT OR CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF THE INDEX OR ANY DATA INCLUDED THEREIN.

©2017 Barclays. Used with Permission.

Source: Barclays Global Family of Indices. Copyright 2017, Barclays. All rights reserved.

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Glossary of Investment Terms

Active Management. An investment approach that seeks to exceed the average returns of a particular financial market or market segment. In selecting securities to buy and sell, active managers may rely on, among other things, research, market forecasts, quantitative models, and their own judgment and experience.

Balanced Composite Index. An index that is weighted 60% MSCI US Broad Market Index and 40% Bloomberg Barclays U.S. Aggregate Bond Index through December 31, 2009; 60% MSCI US Broad Market Index and 40% Bloomberg Barclays U.S. Aggregate Float Adjusted Index through January 14, 2013; and 60% CRSP US Total Market Index and 40% Bloomberg Barclays U.S. Aggregate Float Adjusted Index thereafter.

Bond. A debt security (IOU) issued by a corporation, a government, or a government agency in exchange for the money the bondholder lends it. In most instances, the issuer agrees to pay back the loan by a specific date and generally to make regular interest payments until that date.

Capital Gains Distribution. Payment to mutual fund shareholders of gains realized on securities that a fund has sold at a profit, minus any realized losses.

Common Stock. A security representing ownership rights in a corporation.

Coupon Rate. The interest rate paid by the issuer of a debt security until its maturity. It is expressed as an annual percentage of the face value of the security.

Dividend Distribution. Payment to mutual fund shareholders of income from interest or dividends generated by a fund’s investments.

Duration. A measure of the sensitivity of bond—and bond fund—prices to interest rate movements. For example, if a bond has a duration of two years, its price would fall by approximately 2% when interest rates rise by 1%. On the other hand, the bond’s price would rise by approximately 2% when interest rates fall by 1%.

Expense Ratio. A fund’s total annual operating expenses expressed as a percentage of the fund’s average net assets. The expense ratio includes management and administrative expenses, but it does not include the transaction costs of buying and selling portfolio securities.

Face Value. The amount to be paid at a bond’s maturity; also known as the par value or principal.

Fixed Income Security. An investment, such as a bond, representing a debt that must be repaid by a specified date, and on which the borrower must pay a fixed, variable, or floating rate of interest.

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Float-Adjusted Index. An index that weights its constituent securities based on the value of the constituent securities that are available for public trading, rather than the value of all constituent securities. Some portion of an issuer’s securities may be unavailable for public trading because, for example, those securities are owned by company insiders on a restricted basis or by a government agency. By excluding unavailable securities, float-adjusted indexes can produce a more accurate picture of the returns actually experienced by investors in the measured market.

Inception Date. The date on which the assets of a fund (or one of its share classes) are first invested in accordance with the fund’s investment objective. For funds with a subscription period, the inception date is the day after that period ends. Investment performance is generally measured from the inception date.

Indexing. A low-cost investment strategy in which a mutual fund attempts to track—rather than outperform—a specified market benchmark, or “index.”

Investment-Grade Bond. A debt security whose credit quality is considered by independent bond-rating agencies, or through independent analysis conducted by a fund’s advisor, to be sufficient to ensure timely payment of principal and interest under current economic circumstances. Debt securities rated in one of the four highest rating categories are considered investment-grade. Other debt securities may be considered by an advisor to be investment-grade.

Median Market Capitalization. An indicator of the size of companies in which a fund invests; the midpoint of market capitalization (market price x shares outstanding) of a fund’s stocks, weighted by the proportion of the fund’s assets invested in each stock. Stocks representing half of the fund’s assets have market capitalizations above the median, and the rest are below it.

MSCI US Broad Market Index. An index that tracks virtually all stocks that trade in the U.S. stock market.

Mutual Fund. An investment company that pools the money of many people and invests it in a variety of securities in an effort to achieve a specific objective over time.

New York Stock Exchange (NYSE). A stock exchange based in New York City that is open for regular trading on business days, Monday through Friday, from 9:30 a.m. to 4 p.m., Eastern time. Net asset values (NAVs) are calculated each business day as of the close of regular trading on the NYSE. In the rare event the NYSE experiences unanticipated trade disruptions and is unavailable at the close of the trading day, NAVs will be calculated as of the close of regular trading on the Nasdaq (or another alternate exchange if the Nasdaq is unavailable), generally 4 p.m., Eastern time.

Securities. Stocks, bonds, money market instruments, and other investments.

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Spliced Bloomberg Barclays U.S. Aggregate Float Adjusted Index. An index that reflects performance of the Bloomberg Barclays U.S. Aggregate Bond Index (not float-adjusted) through December 31, 2009, and the Bloomberg Barclays U.S. Aggregate Float Adjusted Index thereafter.

Spliced Total Stock Market Index. An index that reflects performance of the MSCI US Broad Market Index through June 2, 2013, and the CRSP US Total Market Index thereafter.

Total Return. A percentage change, over a specified time period, in a mutual fund’s net asset value, assuming the reinvestment of all distributions of dividends and capital gains.

Volatility. The fluctuations in value of a mutual fund or other security. The greater a fund’s volatility, the wider the fluctuations in its returns.

Yield. Income (interest or dividends) earned by an investment, expressed as a percentage of the investment’s price.

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P.O. Box 2600

Valley Forge, PA 19482-2600

Connect with Vanguard^® > vanguard.com

For More Information

If you would like more information about Vanguard Balanced Index Fund, the following documents are available free upon request:

Annual/Semiannual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semiannual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Statement of Additional Information (SAI)

The SAI provides more detailed information about the Fund and is incorporated by reference into (and thus legally a part of) this prospectus.

To receive a free copy of the latest annual or semiannual report or the SAI, or to request additional information about the Fund or other Vanguard funds, please visit vanguard.com or contact us as follows:

If you are an individual investor:

The Vanguard Group

Investor Information Department P.O. Box 2600 Valley Forge, PA 19482-2600 Telephone: 800-662-7447

Text telephone for people with hearing impairment: 800-749-7273

If you are a participant in an employer-sponsored plan:

The Vanguard Group Participant Services P.O. Box 2900 Valley Forge, PA 19482-2900 Telephone: 800-523-1188

Text telephone for people with hearing impairment: 800-749-7273

If you are a current Vanguard shareholder and would like information about your account, account transactions, and/or account statements, please call:

Client Services Department Telephone: 800-662-2739

Text telephone for people with hearing impairment: 800-749-7273

Information Provided by the Securities and Exchange Commission (SEC)

You can review and copy information about the Fund (including the SAI) at the SEC’s Public Reference Room in Washington, DC. To find out more about this public service, call the SEC at 202-551-8090. Reports and other information about the Fund are also available in the EDGAR database on the SEC’s website at www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following email address: [email protected], or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

Fund’s Investment Company Act file number: 811-58431

© 2017 The Vanguard Group, Inc. All rights reserved. Vanguard Marketing Corporation, Distributor.

P 002 042017

Fund Summary

Investment Objective

With 60% of its assets, the Fund seeks to track the performance of a benchmark index that measures the investment return of the overall U.S. stock market. With 40% of its assets, the Fund seeks to track the performance of a broad, market-weighted bond index.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Institutional Shares of the Fund.

Example

The following example is intended to help you compare the cost of investing in the Fund’s Institutional Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund’s shares. This example assumes that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

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Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense example, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 44% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of two benchmark indexes. The Fund invests by sampling its target indexes, meaning that it holds a range of securities that, in the aggregate, approximates the full indexes in terms of key characteristics.

With approximately 60% of its assets, the Fund seeks to track the investment performance of the CRSP US Total Market Index, which represents approximately 100% of the investable U.S. stock market and includes large-, mid-, small-, and micro-cap stocks regularly traded on the New York Stock Exchange and Nasdaq. The Fund samples the Index by holding a broadly diversified collection of stocks that, in the aggregate, approximates the full Index.

With approximately 40% of its assets, the Fund seeks to track the investment performance of the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, which represents a wide spectrum of public, investment-grade, taxable, fixed income securities in the United States—including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed and asset-backed securities—all with maturities of more than 1 year. At least 80% of the bond portion of the Fund is invested in bonds held in the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, and all of the Fund’s bond holdings are selected through the sampling process. The bond portion of the Fund maintains a dollar-weighted average maturity consistent with that of the Index, which generally ranges between 5 and 10 years and, as of December 31, 2016, was 8.3 years.

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Principal Risks

The Fund is subject to the risks associated with the stock and bond markets, any of which could cause an investor to lose money. However, because stock and bond prices can move in different directions or to different degrees, the Fund’s bond holdings may counteract some of the volatility experienced by the Fund’s stock holdings.

• With approximately 60% of its assets allocated to stocks, the Fund is proportionately subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target stock index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• With approximately 40% of its assets allocated to bonds, the Fund is proportionately subject to bond risks, including interest rate risk, which is the chance that bond prices will decline because of rising interest rates; income risk, which is the chance that the Fund’s income will decline because of falling interest rates; credit risk, which is the chance that a bond issuer will fail to pay interest or principal in a timely manner or that negative perceptions of the issuer’s ability to make such payments will cause the price of that bond to decline; and call risk, which is the chance that during periods of falling interest rates, issuers of callable bonds may call (redeem) securities with higher coupon rates or interest rates before their maturity dates. The Fund would then lose any price appreciation above the bond’s call price and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such redemptions and subsequent reinvestments would also increase the Fund’s portfolio turnover rate.

• The Fund is also subject to index sampling risk, which is the chance that the securities selected for the Fund will not provide investment performance matching that of the Fund’s target indexes.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

3

Annual Total Returns

The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional Shares compare with those of relevant market indexes and other comparative indexes, which have investment characteristics similar to those of the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.

Annual Total Returns — Vanguard Balanced Index Fund Institutional Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 11.31% (quarter ended September 30, 2009), and the lowest return for a quarter was –12.49% (quarter ended December 31, 2008).

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Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

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Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William A. Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the stock portion of the Fund since 2016.

Gerard C. O’Reilly, Principal of Vanguard. He has co-managed the stock portion of the Fund since 2016.

Joshua C. Barrickman, CFA, Principal of Vanguard and head of Vanguard’s Fixed Income Indexing Americas. He has co-managed the bond portion of the Fund since 2013.

Christopher E. Wrazen, CFP, Portfolio Manager at Vanguard. He has co-managed the bond portion of the Fund since 2015.

Purchase and Sale of Fund Shares

You may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The minimum investment amount required to open and maintain a Fund account for Institutional Shares is $5 million. The minimum investment amount required to add to an existing Fund account is generally $1. If you are investing through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how to participate in your plan.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply.

Payments to Financial Intermediaries

The Fund and its investment advisor do not pay financial intermediaries for sales of Fund shares.

6

Investing in Index Funds

What Is Indexing?

Indexing is an investment strategy for tracking the performance of a specified market benchmark, or “index.” An index is a group of securities whose overall performance is used as a standard to measure the investment performance of a particular market. There are many types of indexes. Some represent entire markets—such as the U.S. stock market or the U.S. bond market. Other indexes cover market segments—such as small-capitalization stocks or short-term bonds. The index sponsor determines the securities to include in the index, the weighting of each security in the index, and the appropriate time to make changes to the composition of the index. One cannot invest directly in an index.

An index fund holds all, or a representative sample, of the securities that make up its target index. Index funds attempt to mirror the performance of the target index, for better or worse. However, an index fund generally does not perform exactly like its target index. For example, like all mutual funds, index funds have operating expenses and transaction costs. Market indexes do not, and therefore they will usually have a slight performance advantage over funds that track them.

Index funds typically have the following characteristics:

• Variety of investments. Most Vanguard index funds generally invest in the securities of a variety of companies and industries.

• Relative performance consistency. Because they seek to track market benchmarks, index funds usually do not perform dramatically better or worse than their benchmarks.

• Low cost. Index funds are inexpensive to run compared with actively managed funds.

They have low or no research costs and typically keep trading activity—and thus brokerage commissions, dealer markups, and other transaction costs—to a minimum compared with actively managed funds.

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More on the Fund

This prospectus describes the principal risks you would face as a Fund shareholder. It is important to keep in mind one of the main axioms of investing: generally, the higher the risk of losing money, the higher the potential reward. The reverse, also, is generally true: the lower the risk, the lower the potential reward. As you consider an investment in any mutual fund, you should take into account your personal tolerance

for fluctuations in the securities markets. Look for this symbol throughout the prospectus. It is used to mark detailed information about the more significant risks that you would confront as a Fund shareholder. To highlight terms and concepts important to mutual fund investors, we have provided Plain Talk^® explanations along the way. Reading the prospectus will help you decide whether the Fund is the right investment for you. We suggest that you keep this prospectus for future reference.

Share Class Overview

This prospectus offers the Fund’s Institutional Shares, which are generally for investors who invest a minimum of $5 million. A separate prospectus offers the Fund’s Investor Shares and Admiral^TM Shares, which generally have investment minimums of $3,000 and $10,000, respectively.

All share classes offered by the Fund have the same investment objective, strategies, and policies. However, different share classes have different expenses; as a result, their investment performances will differ.

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The following sections explain the principal investment strategies and policies that the Fund uses in pursuit of its objective. The Fund‘s board of trustees, which oversees the Fund’s management, may change investment strategies or policies in the interest of shareholders without a shareholder vote, unless those strategies or policies are designated as fundamental. Note that the Fund’s investment objective is not fundamental and may be changed without a shareholder vote.

Market Exposure

Stocks

Approximately 60% of the Fund’s assets are invested in stocks.

The Fund is subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target stock index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

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To illustrate the volatility of stock prices, the following table shows the best, worst, and average annual total returns for the U.S. stock market over various periods as measured by the S&P 500 Index, a widely used barometer of U.S. stock market activity. Total returns consist of dividend income plus change in market price. Note that the returns shown do not include the costs of buying and selling stocks or other expenses that a real-world investment portfolio would incur.

The table covers all of the rolling 1-, 5-, 10-, and 20-year periods from 1926 through 2016. You can see, for example, that although the average annual return on common stocks for all of the 5-year periods was 10.1%, average annual returns for individual 5-year periods ranged from –12.4% (from 1928 through 1932) to 28.6% (from 1995 through 1999). These average annual returns reflect past performance of common stocks; you should not regard them as an indication of future performance of either the stock market as a whole or the Fund in particular.

Although the Fund will include a broadly diversified collection of stocks in the CRSP US Total Market Index, it will not include all of the securities in the Index. Instead, the Fund will invest in a representative sample of stocks.

Stocks of publicly traded companies and funds that invest in stocks are often classified according to market value, or market capitalization. These classifications typically include small-cap, mid-cap, and large-cap. It is important to understand that market capitalization ranges change over time. Also, interpretations of size vary, and there are no “official” definitions of small-, mid-, and large-cap, even among Vanguard fund advisors. The asset-weighted median market capitalization of the Fund’s stock holdings as of December 31, 2016, was $54.1 billion.

Although the CRSP US Total Market Index is dominated by large-cap stocks (those tracked by the S&P 500 Index), mid-, small-, and micro-cap stocks are also represented. As of December 31, 2016, approximately 17% of the market value of the CRSP US Total Market Index was made up of securities that were not in the S&P 500 Index. Historically, mid-, small-, and micro-cap stocks have been more volatile than—and at times have performed quite differently from—large-cap stocks.

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Bonds

Approximately 40% of the Fund’s assets are invested in bonds.

The Fund is subject to interest rate risk, which is the chance that bond prices will decline because of rising interest rates. Interest rate risk should be moderate for the Fund because the Fund invests only a portion of its assets in bonds and because the average term of the Fund’s bond portfolio is generally intermediate-term. The prices of intermediate-term bonds are less sensitive to interest rate changes than are the prices of long-term bonds.

Although bonds are often thought to be less risky than stocks, there have been periods when bond prices have fallen significantly because of rising interest rates. For instance, prices of long-term bonds fell by almost 48% between December 1976 and September 1981.

To illustrate the relationship between bond prices and interest rates, the following table shows the effect of a 1% and a 2% change (both up and down) in interest rates on the values of three noncallable bonds (i.e., bonds that cannot be redeemed by the issuer) of different maturities, each with a face value of $1,000.

These figures are for illustration only; you should not regard them as an indication of future performance of the bond market as a whole or the Fund in particular.

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Changes in interest rates can affect bond income as well as bond prices.

The Fund is subject to income risk, which is the chance that the Fund’s income will decline because of falling interest rates. A fund holding bonds will experience a decline in income when interest rates fall because the fund then must invest new cash flow and cash from maturing bonds in lower-yielding bonds.

Although income risk for short- and intermediate-term bonds—like those held by the Fund—is considered moderate, this risk should be low for the Fund because it invests only a portion of its assets in bonds.

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The Fund is subject to credit risk, which is the chance that a bond issuer will fail to pay interest or principal in a timely manner or that negative perceptions of the issuer’s ability to make such payments will cause the price of that bond to decline.

Credit risk should be low for the Fund because it purchases only bonds that are of investment-grade quality.

The Fund is subject to call risk, which is the chance that during periods of falling interest rates, issuers of callable bonds may call (redeem) securities with higher coupon rates or interest rates before their maturity dates. The Fund would then lose any price appreciation above the bond’s call price and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such redemptions and subsequent reinvestments would also increase the Fund’s portfolio turnover rate.

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The Fund is also subject to prepayment risk, which is the chance that during periods of falling interest rates, homeowners will refinance their mortgages before their maturity dates, resulting in prepayment of mortgage-backed securities held by the Fund. The Fund would then lose any price appreciation above the mortgage’s principal and would be forced to reinvest the unanticipated proceeds at lower interest rates, resulting in a decline in the Fund’s income. Such prepayments and subsequent reinvestments would also increase the Fund’s portfolio turnover rate. Because the Fund invests only a portion of its assets in callable bonds and mortgage-backed securities, call risk and prepayment risk for the Fund should be low.

The Fund is subject to extension risk. Extension risk is the chance that during periods of rising interest rates, certain debt securities will be paid off substantially more slowly than originally anticipated, and the value of those securities may fall. For funds that invest in mortgage-backed securities, extension risk is the chance that during periods of rising interest rates, homeowners will prepay their mortgages at slower rates. Extension risk should be low for the Fund because it invests only a portion of its assets in bonds.

To a limited extent, the Fund is also exposed to event risk, which is the chance that corporate fixed income securities held by the Fund may suffer a substantial decline in credit quality and market value because of a corporate restructuring or another corporate event.

The Fund’s bond holdings may help to reduce—but not eliminate—some of the stock market volatility that may be experienced by the Fund. Likewise, changes in interest rates may not have as dramatic an effect on the Fund as they would on a fund made up entirely of bonds. The Fund’s balanced portfolio, in the long run, should result in less investment risk—and a lower investment return—than a fund investing exclusively in common stocks.

Security Selection

Index sampling strategy. Because it would be very expensive and inefficient to buy and sell all the securities held in its target indexes, the Fund uses an index “sampling” technique to select securities. Using computer programs, the Fund generally selects a representative sample of securities that approximates the full target indexes in terms of key risk factors and other characteristics. In its stock portion, the Fund holds a broadly diversified collection of stocks that approximates the CRSP US Total Market Index in terms of factors such as industry weightings, market capitalization, and other financial characteristics of stocks. In its bond portion, the Fund considers factors such as duration, cash flow, quality, and callability of the underlying bonds when sampling the Bloomberg Barclays U.S. Aggregate Float Adjusted Index. In addition, the Fund’s bond portion keeps industry sector and subsector exposure within tight boundaries compared with that of the Index.

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Because the Fund does not hold all the securities in its target indexes, some of the securities (and issuers) that are held will likely be overweighted compared with the target indexes.

The Fund is subject to index sampling risk, which is the chance that the securities selected for the Fund will not provide investment performance matching that of the Fund’s target indexes.

Types of bonds. The Fund’s target index for bonds, the Bloomberg Barclays U.S. Aggregate Float Adjusted Index, represents a wide spectrum of investment-grade fixed income securities in the United States—including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed and asset-backed securities—all with maturities of more than 1 year.

As of December 31, 2016, the Fund’s bond portion was made up of the following types of bonds:

An explanation of each type of bond follows:

• U.S. government and agency bonds represent loans by investors to the U.S.

Treasury or a wide variety of government agencies and instrumentalities. Timely payment of principal and interest on U.S. Treasury bonds is always guaranteed by the full faith and credit of the U.S. government; many (but not all) agency bonds have the same guarantee. The market values of U.S. government and agency securities and U.S. Treasury securities are subject to fluctuation.

• Corporate bonds are IOUs issued by businesses that want to borrow money for some purpose—often to develop a new product or service, to expand into a new market, or to buy another company. As with other types of bonds, the issuer promises to repay the principal on a specific date and to make interest payments in the meantime. The amount of interest offered depends both on market conditions and on the financial health of the corporation issuing the bonds; a company whose credit rating is not strong will have to offer a higher interest rate to obtain buyers for its bonds. Corporate bonds include securities that are backed by a pool of underlying assets (asset-backed securities) or commercial mortgages (commercial mortgage-backed bonds). The Fund expects to purchase only investment-grade corporate bonds.

• Mortgage-backed securities represent interests in underlying pools of mortgages.

Unlike ordinary bonds, which generally pay a fixed rate of interest at regular intervals and then repay principal upon maturity, mortgage-backed securities pass through both

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interest and principal from underlying mortgages as part of their regular payments. Because the mortgages underlying the securities can be prepaid at any time by homeowners or corporate borrowers, mortgage-backed securities are subject to prepayment risk. These types of securities are issued by a number of government agencies, including the Government National Mortgage Association (GNMA), the Federal Home Loan Mortgage Corporation (FHLMC), and the Federal National Mortgage Association (FNMA). GNMAs are guaranteed by the full faith and credit of the U.S. government as to the timely payment of principal and interest; mortgage-backed securities issued by other government agencies or private corporations are not.

The Fund may also invest in conventional mortgage-backed securities—which are packaged by private corporations and are not guaranteed by the U.S. government—and enter into mortgage-dollar-roll transactions. In a mortgage-dollar-roll transaction, a fund sells mortgage-backed securities to a dealer and simultaneously agrees to purchase similar securities in the future at a predetermined price. These transactions simulate an investment in mortgage-backed securities and have the potential to enhance the Fund’s returns and reduce its administrative burdens, compared with holding mortgage-backed securities directly. These transactions may increase a fund’s portfolio turnover rate. Mortgage dollar rolls will be used only if consistent with the Fund’s investment objective and risk profile.

• International dollar-denominated bonds are bonds denominated in U.S. dollars and issued by foreign governments and companies. To the extent that it owns foreign bonds, the Fund is subject to country risk, which is the chance that world events—such as political upheaval, financial troubles, or natural disasters—will adversely affect the value and/or liquidity of securities issued by companies in foreign countries. Because the bond’s value is designated in dollars rather than in the currency of the issuer’s country, the investor is not exposed to currency risk; rather, the issuer assumes the risk, usually to attract U.S. investors.

Other Investment Policies and Risks

The Fund reserves the right to substitute a different index for either of the indexes that it currently tracks if a current index is discontinued, if the Fund’s agreement with the sponsor of a current index is terminated, or for any other reason determined in good faith by the Fund’s board of trustees. In any such instance, the substitute index would represent the same market segment as the current index.

The Fund may invest in foreign stocks to the extent necessary to carry out its investment strategy of holding a representative sample of the stocks that make up the index it tracks. It is not expected that the Fund will invest more than 5% of its assets in foreign stocks.

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Up to 20% of the bond portion of the Fund may be used to purchase nonpublic, investment-grade securities, generally referred to as 144A securities, as well as smaller public issues or medium-term notes not included in the Bloomberg Barclays U.S. Aggregate Float Adjusted Index because of the size of the issue. Subject to the same 20% limit, the Fund also may invest in relatively conservative classes of collateralized mortgage obligations (CMOs), which offer a high degree of cash-flow predictability and a low level of vulnerability to mortgage prepayment risk. To reduce credit risk, these CMOs are purchased only if issued by agencies of the U.S. government or by private companies that carry high-quality investment-grade ratings. The vast majority of any such securities will have characteristics and risks similar to those in the Index.

The Fund may invest, to a limited extent, in derivatives. Generally speaking, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, a bond, or a currency), a physical asset (such as gold, oil, or wheat), a market index (such as the S&P 500 Index), or a reference rate (such as LIBOR). Investments in derivatives may subject the Fund to risks different from, and possibly greater than, those of investments directly in the underlying securities or assets. The Fund will not use derivatives for speculation or for the purpose of leveraging (magnifying) investment returns.

The Fund may purchase money market instruments and certain derivatives in order to manage cash flow into and out of the Fund, reduce the Fund’s transaction costs, or add value when these instruments are favorably priced.

The Fund may invest a small portion of its assets in equity futures and fixed income futures, which are types of derivatives, and/or shares of stock and bond exchange-traded funds (ETFs). These futures and ETFs typically provide returns similar to those of the stocks and bonds listed in the index, or in a subset of the index, tracked by the Fund. The Fund may purchase futures or ETFs when doing so will reduce the Fund’s transaction costs, facilitate cash management, mitigate risk, or have the potential to add value because the instruments are favorably priced. Vanguard receives no additional revenue from Fund assets invested in ETF Shares of other Vanguard funds. Fund assets invested in ETF Shares are excluded when allocating to the Fund its share of the costs of Vanguard operations.

Cash Management

The Fund‘s daily cash balance may be invested in one or more Vanguard CMT Funds, which are very low-cost money market funds. When investing in a Vanguard CMT Fund, the Fund bears its proportionate share of the expenses of the CMT Fund in which it invests. Vanguard receives no additional revenue from Fund assets invested in a Vanguard CMT Fund.

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Temporary Investment Measures

The Fund may temporarily depart from its normal investment policies and strategies when the advisor believes that doing so is in the Fund‘s best interest, so long as the alternative is consistent with the Fund‘s investment objective. For instance, the Fund may invest beyond its normal limits in derivatives or exchange-traded funds that are consistent with the Fund‘s objective when those instruments are more favorably priced or provide needed liquidity, as might be the case when the Fund receives large cash flows that it cannot prudently invest immediately.

Frequent Trading or Market-Timing

Background. Some investors try to profit from strategies involving frequent trading of mutual fund shares, such as market-timing. For funds holding foreign securities, investors may try to take advantage of an anticipated difference between the price of the fund’s shares and price movements in overseas markets, a practice also known as time-zone arbitrage. Investors also may try to engage in frequent trading of funds holding investments such as small-cap stocks and high-yield bonds. As money is shifted into and out of a fund by a shareholder engaging in frequent trading, the fund incurs costs for buying and selling securities, resulting in increased brokerage and administrative costs. These costs are borne by all fund shareholders, including the long-term investors who do not generate the costs. In addition, frequent trading may interfere with an advisor’s ability to efficiently manage the fund.

Policies to address frequent trading. The Vanguard funds (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) do not knowingly accommodate frequent trading. The board of trustees of each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) has adopted policies and procedures reasonably designed to detect and discourage frequent trading and, in some cases, to compensate the fund for the costs associated with it. These policies and procedures do not apply to Vanguard ETF^® Shares because frequent trading in ETF Shares generally does not disrupt portfolio management or otherwise harm fund shareholders. Although there is no assurance that Vanguard will be able to detect or prevent frequent trading or market-timing in all circumstances, the following policies have been adopted to address these issues:

• Each Vanguard fund reserves the right to reject any purchase request—including exchanges from other Vanguard funds—without notice and regardless of size. For example, a purchase request could be rejected because the investor has a history of frequent trading or if Vanguard determines that such purchase may negatively affect a fund’s operation or performance.

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• Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) generally prohibits, except as otherwise noted in the Investing With Vanguard section, an investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account.

• Certain Vanguard funds charge shareholders purchase and/or redemption fees on transactions.

See the Investing With Vanguard section of this prospectus for further details on Vanguard’s transaction policies.

Each Vanguard fund (other than retail and government money market funds), in determining its net asset value, will use fair-value pricing when appropriate, as described in the Share Price section. Fair-value pricing may reduce or eliminate the profitability of certain frequent-trading strategies.

Do not invest with Vanguard if you are a market-timer.

Turnover Rate

Although the Fund generally seeks to invest for the long term, it may sell securities regardless of how long they have been held. Generally, an index fund sells securities in response to redemption requests or to changes in the composition of its target index or in an effort to manage the fund’s duration. The Financial Highlights section of this prospectus shows historical turnover rates for the Fund. A turnover rate of 100%, for example, would mean that the Fund had sold and replaced securities valued at 100% of its net assets within a one-year period.

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The Fund and Vanguard

The Fund is a member of The Vanguard Group, a family of more than 190 mutual funds holding assets of approximately $3.6 trillion. All of the funds that are members of The Vanguard Group (other than funds of funds) share in the expenses associated with administrative services and business operations, such as personnel, office space, and equipment.

Vanguard Marketing Corporation provides marketing services to the funds. Although shareholders do not pay sales commissions or 12b-1 distribution fees, each fund (other than a fund of funds) or each share class of a fund (in the case of a fund with multiple share classes) pays its allocated share of the Vanguard funds’ marketing costs.

Investment Advisor

The Vanguard Group, Inc. (Vanguard), P.O. Box 2600, Valley Forge, PA 19482, which began operations in 1975, serves as advisor to the Fund through its Equity Index and Fixed Income Groups. As of December 31, 2016, Vanguard served as advisor for approximately $3.1 trillion in assets. Vanguard provides investment advisory services to the Fund on an at-cost basis, subject to the supervision and oversight of the trustees and officers of the Fund.

For the fiscal year ended December 31, 2016, the advisory expenses represented an effective annual rate of 0.01% of the Fund’s average net assets.

For a discussion of why the board of trustees approved the Fund’s investment advisory arrangement, see the most recent semiannual report to shareholders covering the fiscal period ended June 30.

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The managers primarily responsible for the day-to-day management of the Fund are:

William A. Coleman, CFA, Portfolio Manager at Vanguard. He has worked in investment management since joining Vanguard in 2006 and has co-managed the stock portion of the Fund since 2016. Education: B.S., King’s College; M.S., Saint Joseph’s University.

Gerard C. O’Reilly, Principal of Vanguard. He has been with Vanguard since 1992, has managed investment portfolios since 1994, and has co-managed the stock portion of the Fund since 2016. Education: B.S., Villanova University.

Joshua C. Barrickman, CFA, Principal of Vanguard and head of Vanguard’s Fixed Income Indexing Americas. He has been with Vanguard since 1998, has worked in investment management since 1999, has managed investment portfolios since 2005, and has co-managed the bond portion of the Fund since 2013. Education: B.S., Ohio Northern University; M.B.A., Lehigh University.

Christopher E. Wrazen, CFP, Portfolio Manager at Vanguard. He has been with Vanguard since 2004, has worked in investment management since 2008, has managed investment portfolios since 2015, and has co-managed the bond portion of the Fund since 2015. Education: B.S., West Chester University; M.B.A., Drexel University.

The Statement of Additional Information provides information about each portfolio manager’s compensation, other accounts under management, and ownership of shares of the Fund.

Dividends, Capital Gains, and Taxes

Fund Distributions

The Fund distributes to shareholders virtually all of its net income (interest and dividends, less expenses) as well as any net short-term or long-term capital gains realized from the sale of its holdings. Income dividends generally are distributed quarterly in March, June, September, and December; capital gains distributions, if any, generally occur annually in December. In addition, the Fund may occasionally make a supplemental distribution at some other time during the year.

You can receive distributions of income or capital gains in cash, or you can have them automatically reinvested in more shares of the Fund. However, if you are investing through an employer-sponsored retirement or savings plan, your distributions will be automatically reinvested in additional Fund shares.

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Basic Tax Points

Investors in taxable accounts should be aware of the following basic federal income tax points:

• Distributions are taxable to you whether or not you reinvest these amounts in additional Fund shares.

• Distributions declared in December—if paid to you by the end of January—are taxable as if received in December.

• Any dividend distribution or short-term capital gains distribution that you receive is taxable to you as ordinary income. If you are an individual and meet certain holding-period requirements with respect to your Fund shares, you may be eligible for reduced tax rates on “qualified dividend income,” if any, distributed by the Fund.

• Any distribution of net long-term capital gains is taxable to you as long-term capital gains, no matter how long you have owned shares in the Fund.

• Capital gains distributions may vary considerably from year to year as a result of the Fund‘s normal investment activities and cash flows.

• A sale or exchange of Fund shares is a taxable event. This means that you may have a capital gain to report as income, or a capital loss to report as a deduction, when you complete your tax return.

• Any conversion between classes of shares of the same fund is a nontaxable event. By contrast, an exchange between classes of shares of different funds is a taxable event.

• Vanguard (or your intermediary) will send you a statement each year showing the tax status of all of your distributions.

Individuals, trusts, and estates whose income exceeds certain threshold amounts are subject to a 3.8% Medicare contribution tax on “net investment income.” Net investment income takes into account distributions paid by the Fund and capital gains from any sale or exchange of Fund shares.

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Dividend distributions and capital gains distributions that you receive, as well as your gains or losses from any sale or exchange of Fund shares, may be subject to state and local income taxes.

This prospectus provides general tax information only. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. Please consult your tax advisor for detailed information about any tax consequences for you.

General Information

Backup withholding. By law, Vanguard must withhold 28% of any taxable distributions or redemptions from your account if you do not:

• Provide your correct taxpayer identification number.
• Certify that the taxpayer identification number is correct.
• Confirm that you are not subject to backup withholding.

Similarly, Vanguard (or your intermediary) must withhold taxes from your account if the IRS instructs us to do so.

Foreign investors. Vanguard funds offered for sale in the United States (Vanguard U.S. funds), including the Fund offered in this prospectus, are not widely available outside the United States. Non-U.S. investors should be aware that U.S. withholding and estate taxes and certain U.S. tax reporting requirements may apply to any investments in Vanguard U.S. funds. Foreign investors should visit the Non-U.S. Investors page on our website at vanguard.com for information on Vanguard’s non-U.S. products.

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Invalid addresses. If a dividend distribution or capital gains distribution check mailed to your address of record is returned as undeliverable, Vanguard will automatically reinvest the distribution and all future distributions until you provide us with a valid mailing address. Reinvestments will receive the net asset value calculated on the date of the reinvestment.

Share Price

Share price, also known as net asset value (NAV), is calculated each business day as of the close of regular trading on the New York Stock Exchange (NYSE), generally 4 p.m., Eastern time. Each share class has its own NAV, which is computed by dividing the total assets, minus liabilities, allocated to the share class by the number of Fund shares outstanding for that class. On U.S. holidays or other days when the NYSE is closed, the NAV is not calculated, and the Fund does not sell or redeem shares. However, on those days the value of the Fund’s assets may be affected to the extent that the Fund holds securities that change in value on those days (such as foreign securities that trade on foreign markets that are open).

Stocks held by a Vanguard fund are valued at their market value when reliable market quotations are readily available from the principal exchange or market on which they are traded. Such securities are generally valued at their official closing price, the last reported sales price, or if there were no sales that day, the mean between the closing bid and asking prices. Debt securities held by a fund are valued based on information furnished by an independent pricing service or market quotations. When a fund determines that pricing-service information or market quotations either are not readily available or do not accurately reflect the value of a security, the security is priced at its fair value (the amount that the owner might reasonably expect to receive upon the current sale of the security).

The values of any foreign securities held by a fund are converted into U.S. dollars using an exchange rate obtained from an independent third party as of the close of regular trading on the NYSE. The values of any mutual fund shares, including institutional money market fund shares, held by a fund are based on the NAVs of the shares. The values of any ETF shares or closed-end fund shares held by a fund are based on the market value of the shares.

A fund also will use fair-value pricing if the value of a security it holds has been materially affected by events occurring before the fund’s pricing time but after the close of the principal exchange or market on which the security is traded. This most commonly occurs with foreign securities, which may trade on foreign exchanges that close many hours before the fund’s pricing time. Intervening events might be company-specific (e.g., earnings report, merger announcement) or country-specific or regional/global (e.g., natural disaster, economic or political news, act of terrorism,

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interest rate change). Intervening events include price movements in U.S. markets that exceed a specified threshold or that are otherwise deemed to affect the value of foreign securities.

Fair-value pricing may be used for domestic securities—for example, if (1) trading in a security is halted and does not resume before the fund’s pricing time or a security does not trade in the course of a day and (2) the fund holds enough of the security that its price could affect the NAV. A fund may use fair-value pricing with respect to its fixed income securities on bond market holidays when the fund is open for business (such as Columbus Day and Veterans Day).

Fair-value prices are determined by Vanguard according to procedures adopted by the board of trustees. When fair-value pricing is employed, the prices of securities used by a fund to calculate the NAV may differ from quoted or published prices for the same securities.

Vanguard fund share prices are published daily on our website at vanguard.com/prices.

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Financial Highlights

The following financial highlights table is intended to help you understand the Institutional Shares‘ financial performance for the periods shown, and certain information reflects financial results for a single Institutional Share. The total returns in the table represent the rate that an investor would have earned or lost each period on an investment in the Institutional Shares (assuming reinvestment of all distributions). This information has been obtained from the financial statements audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, whose report—along with the Fund’s financial statements—is included in the Fund’s most recent annual report to shareholders. You may obtain a free copy of the latest annual or semiannual report by visiting vanguard.com or by contacting Vanguard by telephone or mail.

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