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Oakmark International Small Cap Fund

OAKMARK INTERNATIONALSMALL CAP FUND

INVESTMENT OBJECTIVE

Oakmark International Small Cap Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy, hold, and sell shares of the Fund.

Shareholder Fees (fees paid directly from your investment) None.

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

Annual Fund Operating Expenses - Oakmark International Small Cap Fund	Investor Class		Advisor Class	Institutional Class	R6 Class
Management fees	0.99%		0.99%	0.99%	0.99%
Distribution (12b-1) fees	none		none	none	none
Total Other Expenses	0.35%		0.19%	0.11%	0.08%
Shareholder Service Plan fees	0.19%	[1]	none	none	none
Other expenses	0.16%		0.19%	0.11%	0.08%
Total Annual Fund Operating Expenses	1.34%		1.18%	1.10%	1.07%

Example.

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses were those reflected in the table, inclusive of any fee waivers and/or expense reimbursements.

Although your actual returns and expenses may be higher or lower, based on these assumptions your expenses would be:

Expense Example - Oakmark International Small Cap Fund - USD ($)	Investor Class	Advisor Class	Institutional Class	R6 Class
1 Year	$ 136	$ 120	$ 112	$ 109
3 Years	425	375	350	340
5 Years	734	649	606	590
10 Years	$ 1,613	$ 1,432	$ 1,340	$ 1,306

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 costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 32% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of common stocks of non-U.S. companies. In determining whether an issuer is a U.S. or non-U.S. company, the Fund considers various factors including, its country of domicile, the primary stock exchange on which it trades, the location from which the majority of its revenue comes, and its reporting currency. Under normal market conditions, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in the stocks of "small cap companies." A small cap company is one whose market capitalization is no greater than the largest market capitalization of any company included in the S&P EPAC (Europe Pacific Asia Composite) Small Cap Index ($16.38 billion as of December 29, 2023).

The Fund may invest in non-U.S. markets throughout the world, including emerging markets. The Fund considers emerging markets to be markets located in countries classified as emerging or frontier markets by MSCI, and are generally located in the AsiaPacific region, Eastern Europe, the Middle East, Central and South America, and Africa. Ordinarily, the Fund will invest in the securities of at least five countries outside the United States. There are no geographic limits on the Fund's non-U.S. investments.

The Fund uses a value investment philosophy in selecting equity securities. This value investment philosophy is based upon the belief that, over time, a company's stock price converges with the Adviser's estimate of the company's intrinsic value. By "intrinsic value," the Adviser means its estimate of the price a knowledgeable buyer would pay to acquire the entire business. The Adviser believes that investing in securities priced significantly below what it believes is a company's intrinsic value presents the best opportunity to achieve the Fund's investment objective. A company trading below its estimated intrinsic value is sometimes referred to as trading at a discount.

The Adviser uses this value investment philosophy to identify companies that have discounted stock prices compared to what the Adviser believes are the companies' intrinsic values. In assessing such companies, the Adviser looks for the following characteristics, although the companies selected may not have all of these attributes: (1) free cash flows; (2) earnings that are growing and are reasonably predictable; and (3) high level of company management alignment with shareholders.

Key Tenets of the Oakmark Value Investment Philosophy:

1.  Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth.

2.  Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason—because the company just does not grow. The Adviser looks for businesses that are expected to achieve a combination of dividend yield and per-share growth in business value that is above-average.

3.  Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. To facilitate its selection of investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries.

Once the Adviser identifies a stock that it believes is selling at a significant discount to the Adviser's estimated intrinsic value and that the company has one or more of the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated intrinsic value. This means the Adviser sets specific "buy" and "sell" targets for each stock the Fund holds. The Adviser monitors each portfolio holding and adjusts these price targets as warranted to reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds forty to seventy stocks rather than hundreds, and as a result, a higher percentage of the Fund's total assets may at times be invested in a particular region, sector or industry.

PRINCIPAL INVESTMENT RISKS

PERFORMANCE INFORMATION

The bar chart and performance table below can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Investor Class Shares from year to year. The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. The performance table illustrates the volatility of the Fund's historical returns over various lengths of time and shows how the Fund's average annual returns compare with those of one or more broad measures of market performance. The indices, which are described in "Descriptions of Indices" in the prospectus, have characteristics relevant to the Fund's investment strategy. The Fund's Advisor Class and Institutional Class each commenced operations on November 30, 2016 and the R6 Class commenced operations on December 15, 2020. Updated performance information is available on Oakmark.com or by calling 1-800-OAKMARK (625-6275).

Investor Class Shares Total Returns for Years Ended December 31 (%)

Since 2014, the highest and lowest quarterly returns for the Fund's Investor Class Shares were:
• Highest quarterly return: 27.8%, during the quarter ended December 31, 2022
• Lowest quarterly return: -38.3%, during the quarter ended March 31, 2020

Average Annual Total Returns for Periods Ended December 31, 2023

Average Annual Returns - Oakmark International Small Cap Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Investor Class	19.52%	11.02%	4.83%
Advisor Class	19.72%	11.18%	none
Institutional Class	19.82%	11.25%	none
R6 Class	19.85%	none	none
After Taxes on Distributions | Investor Class	19.00%	10.67%	4.07%
After Taxes on Distributions and Sale of Fund Shares | Investor Class	11.92%	8.78%	3.72%
MSCI World ex U.S. Small Cap Index (Net) (does not reflect the deduction of fees, expenses or taxes)	12.62%	7.05%	4.63%
MSCI World Ex U.S. Index (Net) (does not reflect the deduction of fees, expenses or taxes)	17.94%	8.45%	4.32%
Lipper International Small-Cap Funds Index (does not reflect the deduction of fees, expenses or taxes)	15.67%	7.52%	4.54%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the

after-tax returns may exceed the return before taxes due to an assumed tax benefit from foreign tax credits or any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Investor Class Shares. After-tax returns for Advisor Class Shares, Institutional Class Shares, and R6 Class Shares will vary from returns shown for Investor Class Shares.

[1] Investor Class Shares of the Fund pay a service fee not to exceed 0.25% per annum of the average daily net assets of the Fund's Investor Class Shares. This service fee is paid to third-party intermediaries who provide services for and/or maintain shareholder accounts.