Form 485BPOS VANGUARD ADMIRAL FUNDS

Vanguard S&P 500 Value ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization value stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

1

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 22% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P 500^® Value Index, which represents the value companies, as determined by the index sponsor, of the S&P 500 Index. The Index measures the performance of large-capitalization value stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from large-capitalization value stocks will trail returns from the overall stock market. Large-cap value stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

2

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

3

Annual Total Returns — Vanguard S&P 500 Value Index Fund ETF Shares¹

During the periods shown in the bar chart, the highest return for a calendar quarter was 12.92% (quarter ended March 31, 2012), and the lowest return for a quarter was –16.37% (quarter ended September 30, 2011).

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

4

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

5

Vanguard S&P 500 Growth ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization growth stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

6

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 20% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P 500^® Growth Index, which represents the growth companies, as determined by the index sponsor, of the S&P 500 Index. The Index measures the performance of large-capitalization growth stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from large-capitalization growth stocks will trail returns from the overall stock market. Large-cap growth stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

7

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

8

Annual Total Returns — Vanguard S&P 500 Growth Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 6.26%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 12.22% (quarter ended March 31, 2012), and the lowest return for a quarter was –11.65% (quarter ended September 30, 2011).

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

9

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

10

Vanguard S&P Mid-Cap 400 ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

11

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 11% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P MidCap 400^® Index. The Index measures the performance of mid-capitalization stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from mid-capitalization stocks will trail returns from the overall stock market. Historically, mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

12

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

13

Annual Total Returns — Vanguard S&P Mid-Cap 400 Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 12.28%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 13.46% (quarter ended March 31, 2012), and the lowest return for a quarter was –19.93% (quarter ended September 30, 2011).

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

14

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

15

Vanguard S&P Mid-Cap 400 Value ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization value stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

16

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 26% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P MidCap 400^® Value Index, which represents the value companies, as determined by the index sponsor, of the S&P MidCap 400 Index. The Index measures the performance of mid-capitalization value stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from mid-capitalization value stocks will trail returns from the overall stock market. Historically, mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

17

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

18

Annual Total Returns — Vanguard S&P Mid-Cap 400 Value Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 15.07%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.79% (quarter ended December 31, 2011), and the lowest return for a quarter was –20.98% (quarter ended September 30, 2011).

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

19

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

20

Vanguard S&P Mid-Cap 400 Growth ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization growth stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

21

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 38% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P MidCap 400^® Growth Index, which represents the growth companies, as determined by the index sponsor, of the S&P MidCap 400 Index. The Index measures the performance of mid-capitalization growth stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from mid-capitalization growth stocks will trail returns from the overall stock market. Historically, mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

22

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

23

Annual Total Returns — Vanguard S&P Mid-Cap 400 Growth Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 9.43%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 14.04% (quarter ended March 31, 2012), and the lowest return for a quarter was –18.88% (quarter ended September 30, 2011).

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

24

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

25

Vanguard S&P Small-Cap 600 ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of small-capitalization stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

26

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 15% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P SmallCap 600^® Index. The Index measures the performance of small-capitalization stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from small-capitalization stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Small companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

27

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

28

Annual Total Returns — Vanguard S&P Small-Cap 600 Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 13.79%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 17.07% (quarter ended December 31, 2011), and the lowest return for a quarter was –19.90% (quarter ended September 30, 2011).

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

29

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has co-managed the Fund since 2015.

William Coleman, CFA, Portfolio Manager at Vanguard. He has managed the Fund since 2013 (co-managed since 2015).

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

30

Vanguard S&P Small-Cap 600 Value ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of small-capitalization value stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

31

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 42% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P SmallCap 600^® Value Index, which represents the value companies, as determined by the index sponsor, of the S&P SmallCap 600 Index. The Index measures the performance of small-capitalization value stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from small-capitalization value stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Small companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

32

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

33

Annual Total Returns — Vanguard S&P Small-Cap 600 Value Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 16.46%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 18.53% (quarter ended December 31, 2011), and the lowest return for a quarter was –20.05% (quarter ended September 30, 2011).

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

34

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has co-managed the Fund since 2015.

William Coleman, CFA, Portfolio Manager at Vanguard. He has managed the Fund since 2013 (co-managed since 2015).

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

35

Vanguard S&P Small-Cap 600 Growth ETF

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of small-capitalization growth stocks in the United States.

Fees and Expenses

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

The following example is intended to help you compare the cost of investing in the Fund’s ETF Shares with the cost of investing in other funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $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:

36

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

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 48% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P SmallCap 600^® Growth Index, which represents the growth companies, as determined by the index sponsor, of the S&P SmallCap 600 Index. The Index measures the performance of small-capitalization growth stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target 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.

• Investment style risk, which is the chance that returns from small-capitalization growth stocks will trail returns from the overall stock market. Historically, small-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Small companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

37

Because ETF Shares are traded on an exchange, they are subject to additional risks:

• The Fund’s ETF Shares are listed for trading on NYSE Arca and are bought and sold on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price and the NAV differ significantly. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Although the Fund’s ETF Shares are listed for trading on NYSE Arca, it is possible that an active trading market may not be maintained.

• Trading of the Fund’s ETF Shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of the Fund’s ETF Shares may also be halted if (1) the shares are delisted from NYSE Arca without first being listed on another exchange or (2) NYSE Arca officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

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.

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 ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of the Fund‘s target index, which has 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.

38

Annual Total Returns — Vanguard S&P Small-Cap 600 Growth Index Fund ETF Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 11.29%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 15.80% (quarter ended December 31, 2011), and the lowest return for a quarter was –19.68% (quarter ended September 30, 2011).

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

39

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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has co-managed the Fund since 2015.

William Coleman, CFA, Portfolio Manager at Vanguard. He has managed the Fund since 2013 (co-managed since 2015).

Purchase and Sale of Fund Shares

You can buy and sell ETF Shares of the Fund through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more or less than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, typically in exchange for baskets of securities. For this Fund, the number of ETF Shares in a Creation Unit is 25,000.

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.

40

Investing in Vanguard ETF^® Shares

What Are Vanguard ETF Shares?

Vanguard ETF Shares are an exchange-traded class of shares issued by certain Vanguard mutual funds. ETF Shares represent an interest in the portfolio of stocks or bonds held by the issuing fund. The following ETF Shares are offered through this prospectus:

In addition to ETF Shares, each Fund offers one conventional (not exchange-traded) class of shares. This prospectus, however, relates only to ETF Shares.

How Are Vanguard ETF Shares Different From Conventional Mutual Fund Shares?

Conventional mutual fund shares can be directly purchased from and redeemed with the issuing fund for cash at the net asset value (NAV), typically calculated once a day. ETF Shares, by contrast, cannot be purchased directly from or redeemed directly with the issuing fund by an individual investor. Rather, ETF Shares can only be purchased or redeemed directly from the issuing fund by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks (Creation Units) worth several million dollars, usually in exchange for baskets of securities and not for cash (although some funds issue and redeem Creation Units in exchange for cash or a combination of cash and securities).

An organized secondary trading market is expected to exist for ETF Shares, unlike conventional mutual fund shares, because ETF Shares are listed for trading on a national securities exchange. Individual investors can purchase and sell ETF Shares on the secondary market through a broker. Secondary-market transactions occur not at NAV, but at market prices that change throughout the day based on the supply of and demand for ETF Shares and on changes in the prices of the fund’s portfolio holdings.

The market price of a fund’s ETF Shares typically will differ somewhat from the NAV of those shares. The difference between market price and NAV is expected to be small

41

most of the time, but in times of market disruption or extreme market volatility, the difference may become significant.

How Do I Buy and Sell Vanguard ETF Shares?

ETF Shares of the Funds are listed for trading on NYSE Arca. You can buy and sell ETF Shares on the secondary market in the same way you buy and sell any other exchange-traded security—through a broker. Your broker may charge a commission to execute a transaction. You will also incur the cost of the “bid-ask spread,” which is the difference between the price a dealer will pay for a security and the somewhat higher price at which the dealer will sell the same security. Because secondary-market transactions occur at market prices, you may pay more (premium) or less (discount) than NAV when you buy ETF Shares and receive more or less than NAV when you sell those shares. In times of severe market disruption, the bid-ask spread and premiums/ discounts can increase significantly. Unless imposed by your broker, there is no minimum dollar amount you must invest and no minimum number of ETF Shares you must buy.

Your ownership of ETF Shares will be shown on the records of the broker through which you hold the shares. Vanguard will not have any record of your ownership. Your account information will be maintained by your broker, which will provide you with account statements, confirmations of your purchases and sales of ETF Shares, and tax information. Your broker also will be responsible for ensuring that you receive income and capital gains distributions, as well as shareholder reports and other communications from the fund whose ETF Shares you own. You will receive other services (e.g., dividend reinvestment and average cost information) only if your broker offers these services.

42

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 and other transaction costs—to a minimum compared with actively managed funds.

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More on the Funds and ETF Shares

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 a Fund is the right investment for you. We suggest that you keep this prospectus for future reference.

Share Class Overview

This prospectus offers the Funds’ ETF Shares, an exchange-traded class of shares. Separate prospectuses offer the Funds’ Institutional Shares, which are generally for investors who invest a minimum of $5 million.

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

A Note to Investors

Vanguard ETF Shares can be purchased directly from the issuing Fund only by authorized broker-dealers in exchange for a basket of securities (or, in some cases, for cash or a combination of cash and securities) that is expected to be worth several million dollars. Most individual investors, therefore, will not be able to purchase ETF Shares directly from the Fund. Instead, these investors will purchase ETF Shares on the secondary market with the assistance of a broker.

Plain Talk About Costs of Investing

Costs are an important consideration in choosing a mutual fund. That is because you, as a shareholder, pay a proportionate share of the costs of operating a fund, plus any transaction costs incurred when the fund buys or sells securities. These costs can erode a substantial portion of the gross income or the capital appreciation a fund achieves. Even seemingly small differences in expenses can, over time, have a dramatic effect on a fund‘s performance.

The following sections explain the principal investment strategies and policies that each Fund uses in pursuit of its objective. The Funds‘ board of trustees, which oversees each Fund’s management, may change investment strategies or policies in

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the interest of shareholders without a shareholder vote, unless those strategies or policies are designated as fundamental. Note that each Fund‘s investment objective is not fundamental and may be changed without a shareholder vote. Under normal circumstances, each Fund will invest at least 80% of its assets in the stocks that make up its target index. A Fund may change its 80% policy only upon 60 days’ notice to shareholders.

Market Exposure

Each 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. Each Fund‘s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, each Fund‘s target 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. 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 2015. You can see, for example, that although the average annual return on common stocks for all of the 5-year periods was 10%, 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 Funds in particular.

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Keep in mind that the S&P 500 Index tracks mainly large-cap stocks. Historically, small- and mid-cap stocks (such as those held by the S&P Mid-Cap 400 Index Funds and the S&P Small-Cap 600 Index Funds) have been more volatile than—and at times have performed quite differently from—the large-cap stocks of the S&P 500 Index.

Similarly, indexes that focus on growth stocks or value stocks will not necessarily perform in the same way as the broader S&P 500 Index. Both growth and value stocks have the potential at times to be more volatile than the broader markets.

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, for both companies and stock funds, 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 each Fund’s stock holdings as of August 31, 2016, was:

Each Fund is subject to investment style risk, which is the chance that returns from the types of stocks in which the Fund invests will trail returns from the overall stock market. Specific types of stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

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Plain Talk About Growth Funds and Value Funds

Growth investing and value investing are two styles employed by stock-fund managers. Growth funds generally focus on stocks of companies believed to have above-average potential for growth in revenue, earnings, cash flow, or other similar criteria. These stocks typically have low dividend yields and above-average prices in relation to measures such as earnings and book value. Value funds typically emphasize stocks whose prices are below average in relation to those measures; these stocks often have above-average dividend yields. Value stocks also may remain undervalued by the market for long periods of time. Growth and value stocks have historically produced similar long-term returns, though each style has periods when it outperforms the other.

Security Selection

Each Fund attempts to track the investment performance of a benchmark index that measures the return of a particular market segment. The Funds use the replication method of indexing, meaning that each Fund generally holds the same stocks as its target index and in approximately the same proportions.

Other Investment Policies and Risks

Each Fund reserves the right to substitute a different index for the index it currently tracks if the current index is discontinued, if the Fund‘s agreement with the sponsor of its target 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.

Each Fund may invest in foreign securities to the extent necessary to carry out its investment strategy of holding all, or substantially all, of the stocks that make up the index it tracks. It is not expected that any Fund will invest more than 5% of its assets in foreign securities.

To track their target indexes as closely as possible, the Funds attempt to remain fully invested in stocks. To help stay fully invested and to reduce transaction costs, the Funds may invest, to a limited extent, in derivatives, including equity futures. The Funds may also use derivatives such as total return swaps to obtain exposure to a stock, a basket of stocks, or an index. 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 Funds to risks different from, and possibly greater than, those of investments directly in the underlying securities or assets. The Funds will not use derivatives for speculation or for the purpose of leveraging (magnifying) investment returns.

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Cash Management

Each 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, each 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.

Temporary Investment Measures

Each 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.

Special Risks of Exchange-Traded Shares

ETF Shares are not individually redeemable. They can be redeemed with the issuing Fund at NAV only by authorized broker-dealers and only in large blocks known as Creation Units, which would cost millions of dollars to assemble. Consequently, if you want to liquidate some or all of your ETF Shares, you must sell them on the secondary market at prevailing market prices.

The market price of ETF Shares may differ from NAV. Although it is expected that the market price of an ETF Share typically will approximate its NAV, there may be times when the market price and the NAV differ significantly. Thus, you may pay more (premium) or less (discount) than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares. These discounts and premiums are likely to be greatest during times of market disruption or extreme market volatility.

Vanguard’s website at vanguard.com shows the previous day’s closing NAV and closing market price for each Fund’s ETF Shares. The website also discloses, in the Premium/Discount Analysis section of the ETF Shares’ Price & Performance page, how frequently each Fund’s ETF Shares traded at a premium or discount to NAV (based on closing NAVs and market prices) and the magnitudes of such premiums and discounts.

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An active trading market may not exist. Although Vanguard ETF Shares are listed on a national securities exchange, it is possible that an active trading market may not be maintained. Although this could happen at any time, it is more likely to occur during times of severe market disruption. If you attempt to sell your ETF Shares when an active trading market is not functioning, you may have to sell at a significant discount to NAV. In extreme cases, you may not be able to sell your shares at all.

Trading may be halted. Trading of Vanguard ETF Shares on an exchange may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of ETF Shares may also be halted if (1) the shares are delisted from the listing exchange without first being listed on another exchange or (2) exchange officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

Conversion Privilege

Owners of conventional shares issued by a Fund may convert those shares to ETF Shares of equivalent value of the same fund. Please note that investors who own conventional shares through a 401(k) plan or other employer-sponsored retirement or benefit plan generally may not convert those shares to ETF Shares and should check with their plan sponsor or recordkeeper. ETF Shares, whether acquired through a conversion or purchased on the secondary market, cannot be converted to conventional shares. Also, ETF Shares of one fund cannot be exchanged for ETF Shares of another fund.

You must hold ETF Shares in a brokerage account. Thus, before converting conventional shares to ETF Shares, you must have an existing, or open a new, brokerage account. This account may be with Vanguard Brokerage Services^® (Vanguard Brokerage) or with any other brokerage firm. To initiate a conversion of conventional shares to ETF Shares, please contact your broker.

Vanguard Brokerage does not impose a fee on conversions from Vanguard conventional shares to Vanguard ETF Shares. However, other brokerage firms may charge a fee to process a conversion. Vanguard reserves the right, in the future, to impose a transaction fee on conversions or to limit or terminate the conversion privilege.

Converting conventional shares to ETF Shares is generally accomplished as follows. First, after your broker notifies Vanguard of your request to convert, Vanguard will transfer your conventional shares from your account to the broker’s omnibus account with Vanguard (an account maintained by the broker on behalf of all its customers who hold conventional Vanguard fund shares through the broker). After the transfer, Vanguard’s records will reflect your broker, not you, as the owner of the shares. Next,

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your broker will instruct Vanguard to convert the appropriate number or dollar amount of conventional shares in its omnibus account to ETF Shares of equivalent value, based on the respective NAVs of the two share classes.

Your Fund’s transfer agent will reflect ownership of all ETF Shares in the name of the Depository Trust Company (DTC). The DTC will keep track of which ETF Shares belong to your broker, and your broker, in turn, will keep track of which ETF Shares belong to you.

Because the DTC is unable to handle fractional shares, only whole shares can be converted. For example, if you owned 300.250 conventional shares, and this was equivalent in value to 90.750 ETF Shares, the DTC account would receive 90 ETF Shares. Conventional shares with a value equal to 0.750 ETF Shares (in this example, that would be 2.481 conventional shares) would remain in the broker’s omnibus account with Vanguard. Your broker then could either (1) credit your account with 0.750 ETF Shares or (2) redeem the 2.481 conventional shares for cash at NAV and deliver that cash to your account. If your broker chose to redeem your conventional shares, you would realize a gain or loss on the redemption that must be reported on your tax return (unless you hold the shares in an IRA or other tax-deferred account). Please consult your broker for information on how it will handle the conversion process, including whether it will impose a fee to process a conversion.

If you convert your conventional shares to ETF Shares through Vanguard Brokerage, all conventional shares for which you request conversion will be converted to ETF Shares of equivalent value. Because no fractional shares will have to be sold, the transaction will not be taxable.

Here are some important points to keep in mind when converting conventional shares of a Vanguard fund to ETF Shares:

• The conversion process can take anywhere from several days to several weeks, depending on your broker. Vanguard generally will process conversion requests either on the day they are received or on the next business day. Vanguard imposes conversion blackout windows around the dates when a fund with ETF Shares declares dividends. This is necessary to prevent a shareholder from collecting a dividend from both the conventional share class currently held and also from the ETF share class to which the shares will be converted.

• Until the conversion process is complete, you will remain fully invested in a fund’s conventional shares, and your investment will increase or decrease in value in tandem with the NAV of those shares.

• The conversion transaction is nontaxable except, if applicable, to the very limited extent previously described.

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A precautionary note to investment companies: Vanguard ETF Shares are issued by registered investment companies, and therefore the acquisition of such shares by other investment companies is subject to the restrictions of Section 12(d)(1) of the Investment Company Act of 1940. Vanguard has obtained an SEC exemptive order that allows registered investment companies to invest in the issuing funds beyond the limits of Section 12(d)(1), subject to certain terms and conditions, including the requirement to enter into a participation agreement with Vanguard.

Frequent Trading and Market-Timing

Unlike frequent trading of a Vanguard fund’s conventional (i.e., not exchange-traded) classes of shares, frequent trading of ETF Shares does not disrupt portfolio management, increase the fund’s trading costs, lead to realization of capital gains by the fund, or otherwise harm fund shareholders. The vast majority of trading in ETF Shares occurs on the secondary market. Because these trades do not involve the issuing fund, they do not harm the fund or its shareholders. A few institutional investors are authorized to purchase and redeem ETF Shares directly with the issuing fund. Because these trades typically are effected in kind (i.e., for securities and not for cash), they do not cause any of the harmful effects to the issuing fund (as previously noted) that may result from frequent cash trades. For these reasons, the board of trustees of each fund that issues ETF Shares has determined that it is not necessary to adopt policies and procedures to detect and deter frequent trading and market-timing of ETF Shares.

Portfolio Holdings

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

Turnover Rate

Although the Funds generally seek to invest for the long term, each Fund may sell securities regardless of how long they have been held. Generally, an index fund sells securities in response to redemption requests from shareholders of conventional (not exchange-traded) shares or to changes in the composition of its target index. Turnover rates for large-cap stock index funds tend to be low because large-cap indexes typically do not change significantly from year to year. Turnover rates for mid-cap and small-cap stock index funds tend to be higher than for large-cap stock index funds (although still relatively low, compared with actively managed stock funds) because the indexes they track are more likely to change as a result of companies merging, growing, or failing. The Financial Highlights section of this prospectus shows historical turnover rates for each Fund. A turnover rate of 100%, for example, would mean that a Fund had sold and replaced securities valued at 100% of its net assets within a one-year period. Increased

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cash flow into the S&P Small-Cap 600 Growth Index Fund during the fiscal year ended August 31, 2015, resulted in higher portfolio turnover for that year. The average turnover rate for domestic stock funds was approximately 65%, as reported by Morningstar, Inc., on August 31, 2016.

Plain Talk About Turnover Rate

Before investing in a mutual fund, you should review its turnover rate. This gives an indication of how transaction costs, which are not included in the fund’s expense ratio, could affect the fund’s future returns. In general, the greater the volume of buying and selling by the fund, the greater the impact that brokerage commissions and other transaction costs will have on its return. Also, funds with high turnover rates may be more likely to generate capital gains, including short-term capital gains, that must be distributed to shareholders and will be taxable to shareholders investing through a taxable account.

The Funds and Vanguard

Each Fund is a member of The Vanguard Group, a family of more than 190 mutual funds holding assets of approximately $3.5 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.

Plain Talk About Vanguard’s Unique Corporate Structure

The Vanguard Group is truly a mutual mutual fund company. It is owned jointly by the funds it oversees and thus indirectly by the shareholders in those funds. Most other mutual funds are operated by management companies that may be owned by one person, by a private group of individuals, or by public investors who own the management company’s stock. The management fees charged by these companies include a profit component over and above the companies’ cost of providing services. By contrast, Vanguard provides services to its member funds on an at-cost basis, with no profit component, which helps to keep the funds’ expenses low.

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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 Funds through its Equity Index Group. As of August 31, 2016, Vanguard served as advisor for approximately $2.9 trillion in assets. Vanguard provides investment advisory services to the Funds on an at-cost basis, subject to the supervision and oversight of the trustees and officers of the Funds.

For the fiscal year ended August 31, 2016, the advisory expenses represented an effective annual rate of each Fund’s average net assets as follows: for the S&P 500 Value Index, S&P 500 Growth Index, S&P Mid-Cap 400 Index, S&P Mid-Cap 400 Value Index, S&P Mid-Cap 400 Growth Index, S&P Small-Cap 600 Index Funds, and S&P Small-Cap 600 Value Index Fund 0.02%; and for the S&P Small-Cap 600 Growth Index Fund, 0.01%.

For a discussion of why the board of trustees approved each Fund’s investment advisory arrangement, see the most recent annual reports to shareholders covering the fiscal year ended August 31.

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

Donald M. Butler, CFA, Principal of Vanguard. He has been with Vanguard since 1992; has managed investment portfolios since 1997; and has co-managed the S&P 500 Value Index, S&P 500 Growth Index, S&P Small-Cap 600 Index, S&P Small-Cap 600 Value Index, and S&P Small-Cap 600 Growth Index Funds since 2015. Education: B.S.B.A., Shippensburg University.

William Coleman, CFA, Portfolio Manager at Vanguard. He has worked in investment management since joining Vanguard in 2006; has managed the S&P Small-Cap 600 Index, S&P Small-Cap 600 Value Index, and S&P Small-Cap 600 Growth Index Funds since 2013 (co-managed since 2015); and has co-managed the S&P Mid-Cap 400 Index, S&P Mid-Cap 400 Value Index, and S&P Mid-Cap 400 Growth Index Funds since 2015. Education: B.S., King’s College; M.S., Saint Joseph’s University.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has been with Vanguard since 2006; has worked in investment management since 2008; has managed investment portfolios since 2013; and has co-managed the S&P 500 Value Index, S&P 500 Growth Index, S&P Mid-Cap 400 Index, S&P Mid-Cap 400 Value Index, and S&P Mid-Cap 400 Growth Index Funds since 2015. Education: B.S., Millersville University.

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

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Dividends, Capital Gains, and Taxes

Fund Distributions

Each 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 for the S&P Mid-Cap 400 Index, S&P 500 Value Index, S&P 500 Growth Index, S&P Small-Cap 600 Value Index, and S&P Small-Cap 600 Growth Index Funds generally are distributed quarterly in March, June, September, and December; income dividends for the S&P Mid-Cap 400 Value Index, S&P Mid-Cap 400 Growth Index, and S&P Small-Cap 600 Index Funds generally are distributed annually in December. Capital gains distributions, if any, generally occur annually in December. In addition, each Fund may occasionally make a supplemental distribution at some other time during the year.

Plain Talk About Distributions

As a shareholder, you are entitled to your portion of a fund’s income from interest and dividends as well as capital gains from the fund’s sale of investments. Income consists of both the dividends that the fund earns from any stock holdings and the interest it receives from any money market and bond investments. Capital gains are realized whenever the fund sells securities for higher prices than it paid for them. These capital gains are either short-term or long-term, depending on whether the fund held the securities for one year or less or for more than one year.

Reinvestment of Distributions

In order to reinvest dividend and capital gains distributions, investors in a Fund’s ETF Shares must hold their shares at a broker that offers a reinvestment service. This can be the broker’s own service or a service made available by a third party, such as the broker’s outside clearing firm or the Depository Trust Company (DTC). If a reinvestment service is available, distributions of income and capital gains can automatically be reinvested in additional whole and fractional ETF Shares of the Fund. If a reinvestment service is not available, investors will receive their distributions in cash. To determine whether a reinvestment service is available and whether there is a commission or other charge for using this service, consult your broker.

As with all exchange-traded funds, reinvestment of dividend and capital gains distributions in additional ETF Shares will occur four business days or more after the ex-dividend date (the date when a distribution of dividends or capital gains is deducted from the price of a Fund’s shares). The exact number of days depends on your broker. During that time, the amount of your distribution will not be invested in the Fund and therefore will not share in the Fund’s income, gains, and losses.

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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 ETF 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 ETF 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 ETF Shares.

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

• A sale of ETF 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.

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 of ETF Shares.

Dividend distributions and capital gains distributions that you receive, as well as your gains or losses from any sale of ETF 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.

Share Price and Market 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 Funds do not sell or redeem shares. However, on those days the value of a Fund’s assets may be affected to the

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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).

Remember: If you buy or sell ETF Shares on the secondary market, you will pay or receive the market price, which may be higher or lower than NAV. Your transaction will be priced at NAV only if you purchase or redeem your ETF Shares in Creation Unit blocks (an option available only to certain authorized broker-dealers) or if you convert your conventional fund shares to ETF Shares.

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. When a fund determines that 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). 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.

Certain short-term debt instruments used to manage a fund’s cash may be valued at amortized cost when it approximates fair value. 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.

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 held by a fund are based on the NAVs of the shares. The values of any ETF shares, institutional money market fund shares, or closed-end fund shares held by a fund are based on the market value of the shares.

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.

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

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by a fund to calculate the NAV may differ from quoted or published prices for the same securities.

Vanguard’s website will show the previous day’s closing NAV and closing market price for each Fund’s ETF Shares.

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Financial Highlights

The following financial highlights tables are intended to help you understand each 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 reports—along with each Fund’s financial statements—are included in the Funds’ most recent annual reports to shareholders. You may obtain a free copy of the latest annual or semiannual reports by visiting vanguard.com or by contacting Vanguard by telephone or mail.

Plain Talk About How to Read the Financial Highlights Tables

This explanation uses the S&P 500 Value Index Fund’s ETF Shares as an example. The ETF Shares began fiscal year 2016 with a net asset value (share price) of $83.75 per share. During the year, each ETF Share earned $2.125 from investment income (interest and dividends) and $8.605 from investments that had appreciated in value or that were sold for higher prices than the Fund paid for them.

Shareholders received $2.07 per share in the form of dividend distributions. A portion of each year’s distributions may come from the prior year’s income or capital gains.

The share price at the end of the year was $92.41, reflecting earnings of $10.73 per share and distributions of $2.07 per share. This was an increase of $8.66 per share (from $83.75 at the beginning of the year to $92.41 at the end of the year). For a shareholder who reinvested the distributions in the purchase of more shares, the total return was 13.03% for the year.

As of August 31, 2016, the ETF Shares had approximately $487 million in net assets. For the year, the expense ratio was 0.15% ($1.50 per $1,000 of net assets), and the net investment income amounted to 2.64% of average net assets. The Fund sold and replaced securities valued at 22% of its net assets.

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1 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Calculated based on average shares outstanding.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Calculated based on average shares outstanding.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Calculated based on average shares outstanding.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Calculated based on average shares outstanding.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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1 Calculated based on average shares outstanding.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares, including ETF Creation Units.

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

Morningstar data © 2016 Morningstar, Inc. All Rights Reserved. The information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information. Past performance is no guarantee of future results.

The S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index (the “Indexes”) are products of S&P Dow Jones Indices LLC (“SPDJI”), and have been licensed for use by Vanguard. Standard & Poor’s^® and S&P^® are registered trademarks of Standard & Poor’s Financial Services LLC (“S&P”); Dow Jones^® is a registered trademark of Dow Jones Trademark Holdings LLC (“Dow Jones”); S&P^® and S&P 500^® are trademarks of S&P; and these trademarks have been licensed for use by SPDJI and sublicensed for certain purposes by Vanguard. Vanguard S&P ETFs are not sponsored, endorsed, sold or promoted by SPDJI, Dow Jones, S&P, or any of their respective affiliates (collectively, “S&P Dow Jones Indices”). S&P Dow Jones Indices make no representation or warranty, express or implied, to the owners of the Vanguard S&P ETFs or any member of the public regarding the advisability of investing in securities generally or in Vanguard S&P ETFs particularly or the ability of the S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index to track general market performance. S&P Dow Jones Indices’ only relationship to Vanguard with respect to the S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index is the licensing of the Indexes and certain trademarks, service marks and/or trade names of S&P Dow Jones Indices and/or its licensors. The S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index are determined, composed and calculated by S&P Dow Jones Indices without regard to Vanguard or the Vanguard S&P ETFs. S&P Dow Jones Indices have no obligation to take the needs of Vanguard or the owners of Vanguard S&P ETFs into consideration in determining, composing or calculating the S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index. S&P Dow Jones Indices are not responsible for and have not participated in the determination of the prices, and amount of Vanguard S&P ETFs or the timing of the issuance or sale of Vanguard S&P ETFs or in the determination or calculation of the equation by which Vanguard S&P ETFs are to be converted into cash, surrendered or redeemed, as the case may be. S&P Dow Jones Indices have no obligation or liability in connection with the administration, marketing or trading of Vanguard S&P ETFs. There is no assurance that investment products based on the S&P 500 Value Index, S&P 500 Growth Index, S&P MidCap 400 Index, S&P MidCap 400 Value Index, S&P MidCap 400 Growth Index, S&P SmallCap 600 Index, S&P SmallCap 600 Value Index, and S&P SmallCap 600 Growth Index will accurately track index performance or provide positive investment returns. S&P Dow Jones Indices LLC is not an investment advisor. Inclusion of a security within an index is not a recommendation by S&P Dow Jones Indices to buy, sell, or hold such security, nor is it considered to be investment advice.

S&P DOW JONES INDICES DOES NOT GUARANTEE THE ADEQUACY, ACCURACY, TIMELINESS AND/OR THE COMPLETENESS OF THE INDEXES OR ANY DATA RELATED THERETO OR ANY COMMUNICATION, INCLUDING BUT NOT LIMITED TO, ORAL OR WRITTEN COMMUNICATION (INCLUDING ELECTRONIC COMMUNICATIONS) WITH RESPECT THERETO. S&P DOW JONES INDICES SHALL NOT BE SUBJECT TO ANY DAMAGES OR LIABILITY FOR ANY ERRORS, OMISSIONS, OR DELAYS THEREIN. S&P DOW JONES INDICES MAKE NO EXPRESS OR IMPLIED WARRANTIES, AND EXPRESSLY DISCLAIMS ALL WARRANTIES, OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE OR AS TO RESULTS TO BE OBTAINED BY VANGUARD, OWNERS OF THE VANGUARD S&P ETFS, OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDEXES OR WITH RESPECT TO ANY DATA RELATED THERETO. WITHOUT LIMITING ANY OF THE FOREGOING, IN NO EVENT WHATSOEVER SHALL S&P DOW JONES INDICES BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO, LOSS OF PROFITS, TRADING LOSSES, LOST TIME OR GOODWILL, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, WHETHER IN CONTRACT, TORT, STRICT LIABILITY, OR OTHERWISE. THERE ARE NO THIRD PARTY BENEFICIARIES OF ANY AGREEMENTS OR ARRANGEMENTS BETWEEN S&P DOW JONES INDICES AND VANGUARD, OTHER THAN THE LICENSORS OF S&P DOW JONES INDICES.

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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.

Authorized Participant. Institutional investors that are permitted to purchase Creation Units directly from, and redeem Creation Units directly with, the issuing fund. To be an Authorized Participant, an entity must be a participant in the Depository Trust Company and must enter into an agreement with the fund’s Distributor.

Bid-Ask Spread. The difference between the price a dealer is willing to pay for a security (the bid price) and the somewhat higher price at which the dealer is willing to sell the same security (the ask price).

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.

Creation Unit. A large block of a specified number of ETF Shares. Certain broker-dealers known as “Authorized Participants” may purchase and redeem ETF Shares from the issuing fund in Creation Unit size blocks.

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

Ex-Dividend Date. The date when a distribution of dividends and/or capital gains is deducted from the share price of a mutual fund or stock. On the ex-dividend date, the share price drops by the amount of the distribution per share (plus or minus any market activity).

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.

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.”

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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.

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.

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.

Vanguard S&P Mid-Cap 400 Index Fund

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization stocks in the United States.

Fees and Expenses

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

1

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 invested $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:

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 11% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P MidCap 400^® Index. The Index measures the performance of mid-capitalization stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• 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. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target index may, at times, become focused in stocks of a particular market

2

sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• Investment style risk, which is the chance that returns from mid-capitalization stocks will trail returns from the overall stock market. Historically, mid-cap stocks have been more volatile in price than the large-cap stocks that dominate the overall market, and they often perform quite differently. Mid-size companies tend to have greater stock volatility because, among other things, these companies are more sensitive to changing economic conditions.

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.

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 the Fund‘s target index, which has 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 S&P Mid-Cap 400 Index Fund Institutional Shares¹

1 The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2016, was 12.35%.

During the periods shown in the bar chart, the highest return for a calendar quarter was 13.48% (quarter ended March 31, 2012), and the lowest return for a quarter was –8.52% (quarter ended September 30, 2015).

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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.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

William Coleman, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

Scott E. Geiger, CFA, Portfolio Manager at Vanguard. He has co-managed the Fund since 2015.

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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.

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Vanguard S&P Mid-Cap 400 Value Index Fund

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization value stocks in the United States.

Fees and Expenses

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

6

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 invested $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:

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 26% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the S&P MidCap 400^® Value Index, which represents the value companies, as determined by the index sponsor, of the S&P MidCap 400 Index. The Index measures the performance of mid-capitalization value stocks in the United States. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks