Form 497K BAILLIE GIFFORD FUNDS

Baillie Gifford U.S. Discovery Fund

Before you invest, you may want to review the Fund's full prospectus, which contains more information about the Fund and its risks. You can find the Fund's full prospectus and other information about the Fund, including its statement of additional information ("SAI") and most recent reports to shareholders, online at http://USmutualfund.bailliegifford.com. You can also get this information at no cost by calling 1-844-394-6127 or by emailing [email protected]. This Summary Prospectus incorporates by reference the Fund's entire prospectus and SAI, each dated April 29, 2022, as supplemented or revised, and the financial statements included in the Fund's annual report to shareholders, dated December 31, 2021

Investment Objective

Baillie Gifford U.S. Discovery Fund seeks capital appreciation.

Fees and Expenses

The tables below describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Shareholder Fees

(Fees paid directly from your investment)

Annual Fund Operating Expenses

(Expenses that you pay each year as a percentage of the value of your investment)

^(a)  The Management Fee consists of an Advisory Fee and an Administration and Supervisory Fee paid by the Fund to Baillie Gifford Overseas Limited.

^(b)  While Other Expenses for the last fiscal year were the same for Institutional Class and Class K, Other Expenses for Institutional Class are expected to be higher than those of Class K in the future, since Institutional Class is expected to bear sub-accounting expenses.

^(c)  Baillie Gifford Overseas Limited has contractually agreed to waive its fees and/or bear other expenses of the Fund until April 30, 2023 to the extent that the Fund's Total Annual Fund Operating Expenses (excluding taxes, sub-accounting expenses and extraordinary expenses) exceed 0.82% for Class K and Institutional Class shares. This contractual agreement may only be terminated by the Board of Trustees of the Trust. Because this cap of 0.82% excludes sub-accounting expenses, Total Annual Fund Operating

Expenses After Fee Waiver and/or Expense Reimbursement for Institutional Class are expected to exceed the cap in the future.

Example of Expenses

The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated, regardless of whether or not you redeem your shares at the end of such periods. It also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The example below also applies any contractual expense waivers and/or expense reimbursements to the first year of each period listed in the table.

Although your actual costs may be higher or lower, based on these assumptions, your expenses 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 higher taxes when Fund shares are held in a taxable account. These transaction costs, which are not reflected in "Annual Fund Operating Expenses" or in the "Example of Expenses" above, affect the Fund's performance. The Fund has not yet completed its first full year of operations. During the period from May 1, 2021 to December 31, 2021, the Fund's portfolio turnover rate was 6% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to meet its objective by investing in a portfolio of common stocks and other equity securities of smaller, publicly traded U.S. companies that are perceived to be innovative and entrepreneurial, such as by disrupting existing markets or creating entirely new ones, and that have strong growth potential.

Baillie Gifford U.S. Discovery Fund – Summary Prospectus

In selecting portfolio investments, the portfolio managers seek to discover innovative and entrepreneurial companies through a process that involves considering, among other things, a potential holding's market opportunity, competitive edge, corporate culture, and scalability prospects. The inclusion of "discovery" in the Fund's name does not reflect an intent to invest in any particular type of investment or industry.

When selecting companies for initial inclusion in the portfolio, the portfolio managers focus on publicly traded companies with a market capitalization in the region of $10 billion or lower at the time of initial purchase. Because the Fund is managed in accordance with an established model investment strategy operated by the portfolio managers, the Fund's portfolio is expected to include a number of companies with market capitalizations of greater than $10 billion at the time the Fund commences investment operations. These are companies that had market capitalizations of less than $10 billion at the time of inclusion in the model investment strategy, but which have subsequently grown. In addition, because the Fund expects to continue to hold, and potentially increase its investment in, portfolio companies whose market capitalizations increase subsequent to the initial purchase, the Fund expects over time to have a substantial portion of its portfolio invested in companies with a market capitalization in excess of $10 billion. Under normal circumstances, the Fund invests at least 80% of its assets in securities of small- and mid-capitalization companies, which the Manager defines as companies with market capitalizations of $30 billion or less.

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities of issuers located in the U.S. The Fund invests in equity securities either directly or indirectly, such as through depositary receipts, and may invest in preferred stocks, convertible securities and warrants. The Fund may participate in initial public offerings ("IPOs").

The portfolio managers select companies without being constrained by the Fund's Benchmark, the Russell 2500 Growth Index. The portfolio managers focus on company research and the long-term outlook of companies and industries. Ideas can come from a wide variety of sources, including, but not limited to, research trips, company meetings, and relationships with industry thought leaders and academic institutions. Stock ideas are normally researched to assess a range of factors, including: long-term growth potential, geographic and industry positioning, competitive advantage, management, financial strength and valuation. The intended outcome is a portfolio of between 40 and 75 growth companies with the potential to outperform the benchmark over the long term. The Fund intends to operate as a non-diversified fund, which means that it may invest a relatively large percentage of its assets in a small number of issuers, industries, or sectors. The Fund aims to hold securities for long periods (typically at least 5-10 years), which generally results in relatively low portfolio turnover and is in line with the Fund's long-term investment outlook. Consistent with this investment outlook, the portfolio managers seek to identify companies with the potential to sustain financial growth over the long term. When assessing a company's long-term growth prospects, the portfolio managers consider a range of factors including the environmental, social, and governance characteristics of the company (e.g. their assessment of the company's impact on

society and the environment, purpose, values, business model, culture and operating practices).

Principal Risks

The Fund's net asset value and returns will be impacted by the performance of the underlying investments of the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the Fund.

The principal risks of investing in the Fund (in alphabetical order after the first six risks) are:

—  Small- and Medium-Capitalization Securities Risk – Securities of small- and medium-capitalization companies can be more volatile due to various factors including more limited product lines, financial and management resources and market distribution channels, as well as shorter operating histories and potentially reduced liquidity, especially during market declines, than the securities of larger, more established companies.

—  Growth Stock Risk – The prices of growth stocks may be based largely on expectations of future earnings, and their prices can decline rapidly and significantly in reaction to negative news. Growth stocks may underperform stocks in other broad style categories (and the stock market as a whole) over any period of time and may shift in and out of favor with investors generally, sometimes rapidly, depending on changes in market, economic, and other factors.

—  Investment Style Risk – Baillie Gifford Overseas Limited (the "Manager") actively makes investment decisions for the Fund through bottom-up stock selection. Accordingly, the Fund will have risk characteristics that differ from its benchmark index. The Manager's judgments about the attractiveness, relative value, or potential appreciation of a particular stock may prove to be incorrect and cause the Fund to lose money or underperform compared to its benchmark index. There can be no assurance that the Manager's investment decisions will produce the desired results.

—  Long-Term Investment Strategy Risk – The Fund pursues a long-term investment approach, typically seeking returns over a period of several years. This investment style may cause the Fund to lose money or underperform compared to its benchmark index or other mutual funds over extended periods of time, and the Fund may not perform as expected in the long term. An investment in the Fund may be more suitable for long-term investors who can bear the risk of short- or medium-term fluctuations in the value of the Fund's portfolio. See also "Selected Investment Techniques and Topics—Governance and Sustainability Principles and Guidelines."

—  Geographic Focus Risk – A fund that focuses its investments in a limited number of countries or geographic regions will not offer the same level of diversification of risks as a more broadly global fund because it will be exposed to a smaller geographic area. The performance of a fund that is less diversified across countries or geographic regions will be closely tied to market, currency, economic, political, environmental, or regulatory conditions and developments in

Baillie Gifford U.S. Discovery Fund – Summary Prospectus

the countries or regions in which the fund invests, and may be more volatile than the performance of a more geographically-diversified portfolio.

—  Non-Diversification Risk – The Fund is classified as a "non-diversified" fund. A non-diversified fund may hold a smaller number of portfolio securities, with larger positions in each security it holds, than many other mutual funds. To the extent the Fund invests in a relatively small number of issuers, a decline in the market value of a particular security held by the Fund may affect its value more than if it invested in a larger number of issuers. The value of the Fund's shares may be more volatile than the values of shares of more diversified funds. See also "Focused Investment Risk."

—  Conflicts of Interest Risk – The Manager's relationships with the Fund's institutional investor base may give rise to various conflicts of interest, since the Manager will sometimes have an incentive to favor those shareholders over other shareholders in the Fund. In addition, the Manager serves as investment adviser to various clients other than the Fund, some of whom may pursue strategies that are substantially similar or nearly identical to investment strategies pursued by the Fund. This "side-by-side" management may give rise to various conflicts of interest, including, for example, in connection with the fair allocation of trades among the Manager's clients or the sharing of different, more, or more timely information regarding investment performance, portfolio holdings, strategy developments and/or the Manager's general market outlook. Furthermore, if investment personnel of the Manager hold board or other positions at outside companies, they could be exposed to material non-public information potentially impeding or delaying a Fund's ability to buy or sell certain investments, or they could otherwise be restricted in their ability to participate in a Fund's investment process.

—  Equity Securities Risk – Equity securities may react more strongly to changes in an issuer's financial condition or prospects than other securities of the same issuer. Investing in equity securities indirectly, such as through participatory notes or depositary receipts, may involve other risks such as the risk that the counterparty may default or that the investment does not track the underlying security as expected.

—  ESG Risk – To the extent that the Fund's portfolio managers incorporate environmental, social and/or governance considerations ("ESG Factors") into the Fund's investment process as a part of the Fund's long-term investment approach, the Fund is subject to the risk that it may underperform funds that do not take ESG Factors into account. The consideration of ESG Factors may prioritize long-term rather than short-term returns, and therefore may negatively impact the relative performance of the Fund over the short, medium or even long term depending on how successfully those ESG Factors are incorporated and whether such investments are in or out of favor. In considering ESG Factors, the portfolio managers may be dependent upon information and data obtained through voluntary reporting by issuers or third-party research that may be incomplete, inaccurate or unavailable, which could impact the portfolio managers' assessment of relative risks

and opportunities. See also "Long-Term Investment Strategy Risk" and "Selected Investment Techniques and Topics—Governance and Sustainability Principles and Guidelines."

—  Focused Investment Risk – Should the Fund focus its investments in related, or a limited number of, countries, regions, sectors, or companies, this would create more risk and greater volatility than if the Fund's investments were less focused.

—  Government and Regulatory Risk – Governmental and regulatory authorities in the United States and other countries, have taken, and may in the future take, actions intervening in the markets in which the Fund invests and in the economy more generally. Governmental and regulatory authorities may also act to increase the scope or burden of regulations applicable to the Fund or to the companies in which the Fund invests. The effects of these actions on the markets generally, and Fund's investment program in particular, can be uncertain and could restrict the ability of the Fund to fully implement its investment strategies, either generally, or with respect to certain securities, industries, or countries. By contrast, markets in some non-U.S. countries historically have been subject to little regulation or oversight by governmental or regulatory authorities, which could heighten the risk of loss due to fraud or market failures in those countries. Governments, agencies, or other regulatory bodies in any country may adopt or change laws or regulations that could adversely affect the Fund or the market value of an instrument held by the Fund.

—  Information Technology Risk – Cyber-attacks, disruptions, or failures that affect the Fund's service providers, counterparties, the securities markets generally, other market participants, or issuers of securities held by the Fund may adversely affect the Fund and its shareholders, including by causing losses for the Fund or impairing Fund operations.

—  IPO Risk – The Fund may purchase securities in IPOs. These securities are subject to many of the same risks of investing in companies with smaller market capitalizations. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile.

—  Liquidity Risk – The Fund's investments may be subject to low trading volume, lack of a market maker, contractual lock-in periods or regulatory restrictions, and the Fund may hold large positions in particular securities. As a result, it may not be possible to sell an investment at a particular time or at an acceptable price. Illiquid securities may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value. In some cases, due to unanticipated levels of illiquidity the Fund may seek to meet its redemption obligations wholly or in part by distributions of assets in-kind.

—  Market Disruption and Geopolitical Risk – The value of the Fund's investments could be adversely affected by events that disrupt securities markets and adversely affect global markets and by changes in non-U.S. and U.S. economic and political conditions.

Baillie Gifford U.S. Discovery Fund – Summary Prospectus

—  Market Risk – The value of the Fund's investments will be affected by fluctuations in the stock markets in which the Fund is invested, factors affecting a particular industry or industries, real or perceived adverse economic conditions, changes in interest or currency rates or adverse investor sentiment generally. Declines in securities market prices may reduce the net asset value of the Fund's shares.

—  New and Smaller-Sized Funds Risk – New funds and smaller-sized funds, such as the Fund, will be subject to greater liquidity risk due to their smaller asset bases and may be required to sell securities at disadvantageous times or prices due to a large shareholder redemption. A fund that has been recently formed will have limited or no performance history for investors to evaluate and may not reach or maintain a sufficient asset size to effectively implement its investment strategy.

—  Service Provider Risk – The Fund will be affected by the Manager's investment techniques, analyses, assessments and employee retention. Similarly, adverse events or performance failures at a service provider, such as human error, inadequate controls or insolvency, have the ability to adversely affect the Fund.

—  Valuation Risk – Some portfolio holdings may be valued on the basis of factors other than market quotations. This may occur more often in times of market turmoil or reduced liquidity. Portfolio holdings that are valued using techniques other than market quotations, including "fair valued" securities, may be subject to greater fluctuation in their valuations from one day to the next than if market quotations were used. There is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time.

Performance

The Fund commenced operations on May 1, 2021 and does not have a full calendar year of performance available. Accordingly, performance data is not included. When performance data becomes available, it will be posted to the following website: http://USmutualfund.bailliegifford.com. Past performance (before and after taxes) is not an indication of future performance.

Management

Investment Manager

Baillie Gifford Overseas Limited

Portfolio Managers

Purchasing, Exchanging, and Selling Fund Shares

To purchase, exchange, or redeem shares of the Fund through an intermediary, please contact your intermediary directly.

Other investors may purchase, exchange, or redeem shares on any day the New York Stock Exchange ("NYSE") is open for trading directly from the Fund's transfer agent, Bank of New York Mellon, by written request, as further described in the sections of the Prospectus entitled "Shares—How to Buy or Exchange Shares" and "Shares—How to Sell Shares." The initial and subsequent investment minimums for the Fund shares are as follows:

⁽¹⁾  If you hold shares through a financial intermediary, the financial intermediary may impose its own, different, investment minimums.

The Manager and Baillie Gifford Funds Services LLC ("BGFS"), the Fund's distributor, each reserves the right to waive any minimum in their sole discretion, and to reject any purchase or exchange order for any reason. Additional information regarding restrictions on purchasing or exchanging shares is provided in the section of the Prospectus entitled "Shares—Restrictions on Buying or Exchanging Shares."

Tax

The Fund intends to make distributions that will be taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account, such as an IRA or 401(k) plan. If you are investing through such a tax-advantaged account, you may be taxed later upon withdrawal of monies from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund shares through a broker-dealer or other financial intermediary, the Fund and its related companies may pay the intermediary for services the intermediary provides to Fund shareholders. These payments are not primarily intended to result in the sale of Fund shares. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. In addition to the fees and expenses described in the "Fees and Expenses" section above, your broker-dealer or financial intermediary may charge commissions or other fees on purchases and sales of the Class K or Institutional Class shares of the Fund. Ask your salesperson or visit your financial intermediary's web site for more information.