UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

Certified Shareholder Report of

Registered Management Investment Companies

Investment Company Act File Number: 811-01435

AMCAP Fund

(Exact Name of Registrant as Specified in Charter)

333 South Hope Street

Los Angeles, California 90071

(Address of Principal Executive Offices)

Registrant's telephone number, including area code: (949) 975-5000

Date of fiscal year end: February 28 or 29

Date of reporting period: August 31, 2020

Brian D. Bullard

AMCAP Fund

6455 Irvine Center Drive

Irvine, California 92618

(Name and Address of Agent for Service)

ITEM 1 – Reports to Stockholders

AMCAP Fund®
Semi-annual report for the six months ended August 31, 2020

We take a disciplined, long-term approach
to investing in growth companies

Beginning January 1, 2021, as permitted by regulations adopted by the U.S. Securities and Exchange Commission, we intend to no longer mail paper copies of the fund’s shareholder reports, unless specifically requested from American Funds or your financial intermediary, such as a broker-dealer or bank. Instead, the reports will be made available on the Capital Group website (capitalgroup.com); you will be notified by mail and provided with a website link to access the report each time a report is posted. If you have already elected to receive shareholder reports electronically, you will not be affected by this change and do not need to take any action. If you prefer to receive shareholder reports and other communications electronically, you may update your mailing preferences with your financial intermediary, or enroll in e-delivery at capitalgroup.com (for accounts held directly with the fund).

You may elect to receive paper copies of all future reports free of charge. If you invest through a financial intermediary, you may contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. If you invest directly with the fund, you may inform American Funds that you wish to continue receiving paper copies of your shareholder reports by contacting us at (800) 421-4225. Your election to receive paper reports will apply to all funds held with American Funds or through your financial intermediary.

AMCAP Fund seeks to provide you with long-term growth of capital.

This fund is one of more than 40 offered by Capital Group, home of American Funds, one of the nation’s largest mutual fund families. For nearly 90 years, Capital Group has invested with a long-term focus based on thorough research and attention to risk.

Fund results shown in this report, unless otherwise indicated, are for Class A shares at net asset value. If a sales charge (maximum 5.75%) had been deducted, the results would have been lower. Results are for past periods and are not predictive of results for future periods. Current and future results may be lower or higher than those shown. Prices and returns will vary, so investors may lose money. Investing for short periods makes losses more likely. For current information and month-end results, visit capitalgroup.com.

Here are the average annual total returns on a $1,000 investment with all distributions reinvested for periods ended September 30, 2020 (the most recent calendar quarter-end):

For other share class results, visit capitalgroup.com and americanfundsretirement.com.

The total annual fund operating expense ratio was 0.69% for Class A shares as of the prospectus dated May 1, 2020. The expense ratio is restated to reflect current fees.

Investment results assume all distributions are reinvested and reflect applicable fees and expenses. When applicable, investment results reflect fee waivers, without which results would have been lower. Visit capitalgroup.com for more information.

Refer to the fund prospectus and the Risk Factors section of this report for more information on risks associated with investing in the fund.

Investments are not FDIC-insured, nor are they deposits of or guaranteed by a bank or any other entity, so they may lose value.

Fellow investors:

Results for AMCAP Fund for the periods ended August 31, 2020, are shown in the table below, as well as results of the fund’s benchmark.

For additional information about the fund, its investment results, holdings and portfolio managers, visit capitalgroup.com/individual/investments/fund/AMCPX. You can also access information about Capital Group’s American Funds and read our insights about the markets, retirement, saving for college, investing fundamentals and more at capitalgroup.com.

Results at a glance

For periods ended August 31, 2020, with all distributions reinvested

This summary investment portfolio is designed to streamline the report and help investors better focus on the fund’s principal holdings. See the inside back cover for details on how to obtain a complete schedule of portfolio holdings.

“Other securities” includes all issues that are not disclosed separately in the summary investment portfolio.

Investments in affiliates¹

See notes to financial statements.

See notes to financial statements.

(dollars and shares in thousands, except per-share amounts)

Shares of beneficial interest issued and outstanding (no stated par value) —
unlimited shares authorized (2,040,521 total shares outstanding)

See notes to financial statements.

See notes to financial statements.

See notes to financial statements.

1. Organization

AMCAP Fund (the “fund”) is registered under the Investment Company Act of 1940 as an open-end, diversified management investment company. The fund seeks to provide long-term growth of capital.

The fund has 19 share classes consisting of six retail share classes (Classes A, C, T, F-1, F-2 and F-3), five 529 college savings plan share classes (Classes 529-A, 529-C, 529-E, 529-T and 529-F-1) and eight retirement plan share classes (Classes R-1, R-2, R-2E, R-3, R-4, R-5E, R-5 and R-6). The 529 college savings plan share classes can be used to save for college education. The retirement plan share classes are generally offered only through eligible employer-sponsored retirement plans. The fund’s share classes are described further in the following table:

Holders of all share classes have equal pro rata rights to the assets, dividends and liquidation proceeds of the fund. Each share class has identical voting rights, except for the exclusive right to vote on matters affecting only its class. Share classes have different fees and expenses (“class-specific fees and expenses”), primarily due to different arrangements for distribution, transfer agent and administrative services. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different per-share dividends by each share class.

2. Significant accounting policies

The fund is an investment company that applies the accounting and reporting guidance issued in Topic 946 by the U.S. Financial Accounting Standards Board. The fund’s financial statements have been prepared to comply with U.S. generally accepted accounting principles (“U.S. GAAP”). These principles require the fund’s investment adviser to make estimates and assumptions that affect reported amounts and disclosures. Actual results could differ from those estimates. Subsequent events, if any, have been evaluated through the date of issuance in the preparation of the financial statements. The fund follows the significant accounting policies described in this section, as well as the valuation policies described in the next section on valuation.

Security transactions and related investment income — Security transactions are recorded by the fund as of the date the trades are executed with brokers. Realized gains and losses from security transactions are determined based on the specific identified cost of the securities. In the event a security is purchased with a delayed payment date, the fund will segregate liquid assets sufficient to meet its payment obligations. Dividend income is recognized on the ex-dividend date and interest income is recognized on an accrual basis. Market discounts, premiums and original issue discounts on fixed-income securities are amortized daily over the expected life of the security.

Class allocations — Income, fees and expenses (other than class-specific fees and expenses), realized gains and losses and unrealized appreciation and depreciation are allocated daily among the various share classes based on their relative net assets. Class-specific fees and expenses, such as distribution, transfer agent and administrative services, are charged directly to the respective share class.

Distributions paid to shareholders — Income dividends and capital gain distributions are recorded on the ex-dividend date.

Currency translation — Assets and liabilities, including investment securities, denominated in currencies other than U.S. dollars are translated into U.S. dollars at the exchange rates supplied by one or more pricing vendors on the valuation date. Purchases and sales of investment securities and income and expenses are translated into U.S. dollars at the exchange rates on the dates of such transactions. The effects of changes in exchange rates on investment securities are included with the net realized gain or loss and net unrealized appreciation or depreciation on investments in the fund’s statement of operations. The realized gain or loss and unrealized appreciation or depreciation resulting from all other transactions denominated in currencies other than U.S. dollars are disclosed separately.

In-kind redemptions — The fund normally redeems shares in cash; however, under certain conditions and circumstances, payment of the redemption price wholly or partly with portfolio securities or other fund assets may be permitted. A redemption of shares in-kind is based upon the closing value of the shares being redeemed as of the trade date. Realized gains/losses resulting from redemptions of shares in-kind are reflected separately in the fund’s statement of operations.

3. Valuation

Capital Research and Management Company (“CRMC”), the fund’s investment adviser, values the fund’s investments at fair value as defined by U.S. GAAP. The net asset value of each share class of the fund is generally determined as of approximately 4:00 p.m.

New York time each day the New York Stock Exchange is open.

Methods and inputs — The fund’s investment adviser uses the following methods and inputs to establish the fair value of the fund’s assets and liabilities. Use of particular methods and inputs may vary over time based on availability and relevance as market and economic conditions evolve.

Equity securities are generally valued at the official closing price of, or the last reported sale price on, the exchange or market on which such securities are traded, as of the close of business on the day the securities are being valued or, lacking any sales, at the last available bid price. Prices for each security are taken from the principal exchange or market on which the security trades.

Fixed-income securities, including short-term securities, are generally valued at prices obtained from one or more pricing vendors. Vendors value such securities based on one or more of the inputs described in the following table. The table provides examples of inputs that are commonly relevant for valuing particular classes of fixed-income securities in which the fund is authorized to invest. However, these classifications are not exclusive, and any of the inputs may be used to value any other class of fixed-income security.

When the fund’s investment adviser deems it appropriate to do so (such as when vendor prices are unavailable or deemed to be not representative), fixed-income securities will be valued in good faith at the mean quoted bid and ask prices that are reasonably and timely available (or bid prices, if ask prices are not available) or at prices for securities of comparable maturity, quality and type.

Securities with both fixed-income and equity characteristics, or equity securities traded principally among fixed-income dealers, are generally valued in the manner described for either equity or fixed-income securities, depending on which method is deemed most appropriate by the fund’s investment adviser. The Capital Group Central Cash Fund (“CCF”), a fund within the Capital Group Central Fund Series (“Central Funds”), is valued based upon a floating net asset value, which fluctuates with changes in the value of CCF’s portfolio securities. The underlying securities are valued based on the policies and procedures in CCF’s statement of additional information.

Securities and other assets for which representative market quotations are not readily available or are considered unreliable by the fund’s investment adviser are fair valued as determined in good faith under fair valuation guidelines adopted by authority of the fund’s board of trustees as further described. The investment adviser follows fair valuation guidelines, consistent with U.S. Securities and Exchange Commission rules and guidance, to consider relevant principles and factors when making fair value determinations. The investment adviser considers relevant indications of value that are reasonably and timely available to it in determining the fair value to be assigned to a particular security, such as the type and cost of the security; contractual or legal restrictions on resale of the security; relevant financial or business developments of the issuer; actively traded similar or related securities; conversion or exchange rights on the security; related corporate actions; significant events occurring after the close of trading in the security; and changes in overall market conditions. In addition, the closing prices of equity securities that trade in markets outside U.S. time zones may be adjusted to reflect significant events that occur after the close of local trading but before the net asset value of each share class of the fund is determined. Fair valuations and valuations of investments that are not actively trading involve judgment and may differ materially from valuations that would have been used had greater market activity occurred.

Processes and structure — The fund’s board of trustees has delegated authority to the fund’s investment adviser to make fair value determinations, subject to board oversight. The investment adviser has established a Joint Fair Valuation Committee (the “Fair Valuation Committee”) to administer, implement and oversee the fair valuation process, and to make fair value decisions. The Fair Valuation Committee regularly reviews its own fair value decisions, as well as decisions made under its standing instructions to the investment adviser’s valuation teams. The Fair Valuation Committee reviews changes in fair value measurements from period to period and may, as deemed appropriate, update the fair valuation guidelines to better reflect the results of back testing and address new or evolving issues. The Fair Valuation Committee reports any changes to the fair valuation guidelines to the board of trustees. The fund’s board and audit committee also regularly review reports that describe fair value determinations and methods.

The fund’s investment adviser has also established a Fixed-Income Pricing Review Group to administer and oversee the fixed-income valuation process, including the use of fixed-income pricing vendors. This group regularly reviews pricing vendor information and market data. Pricing decisions, processes and controls over security valuation are also subject to additional internal reviews, including an annual control self-evaluation program facilitated by the investment adviser’s compliance group.

Classifications — The fund’s investment adviser classifies the fund’s assets and liabilities into three levels based on the inputs used to value the assets or liabilities. Level 1 values are based on quoted prices in active markets for identical securities. Level 2 values are based on significant observable market inputs, such as quoted prices for similar securities and quoted prices in inactive markets. Certain securities trading outside the U.S. may transfer between Level 1 and Level 2 due to valuation adjustments resulting from significant market movements following the close of local trading. Level 3 values are based on significant unobservable inputs that reflect the investment adviser’s determination of assumptions that market participants might reasonably use in valuing the securities. The valuation levels are not necessarily an indication of the risk or liquidity associated with the underlying investment. For example, U.S. government securities are reflected as Level 2 because the inputs used to determine fair value may not always be quoted prices in an active market. At August 31, 2020, all of the fund’s investments were classified as Level 1.

4. Risk factors

Investing in the fund may involve certain risks including, but not limited to, those described below.

Market conditions — The prices of, and the income generated by, the common stocks and other securities held by the fund may decline — sometimes rapidly or unpredictably — due to various factors, including events or conditions affecting the general economy or particular industries; overall market changes; local, regional or global political, social or economic instability; governmental, governmental agency or central bank responses to economic conditions; and currency exchange rate, interest rate and commodity price fluctuations.

Economies and financial markets throughout the world are highly interconnected. Economic, financial or political events, trading and tariff arrangements, wars, terrorism, cybersecurity events, natural disasters, public health emergencies (such as the spread of infectious disease) and other circumstances in one country or region could have impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries affected, the value and liquidity of the fund’s investments may be negatively affected by developments in other countries and regions.

Issuer risks — The prices of, and the income generated by, securities held by the fund may decline in response to various factors directly related to the issuers of such securities, including reduced demand for an issuer’s goods or services, poor management performance, major litigation related to the issuer, changes in government regulations affecting the issuer or its competitive environment and strategic initiatives such as mergers, acquisitions or dispositions and the market response to any such initiatives.

Investing in growth-oriented stocks — Growth-oriented common stocks and other equity-type securities (such as preferred stocks, convertible preferred stocks and convertible bonds) may involve larger price swings and greater potential for loss than other types of investments. These risks may be even greater in the case of smaller capitalization stocks.

Investing outside the U.S. — Securities of issuers domiciled outside the U.S., or with significant operations or revenues outside the U.S., may lose value because of adverse political, social, economic or market developments (including social instability, regional conflicts, terrorism and war) in the countries or regions in which the issuers operate or generate revenue. These securities may also lose value due to changes in foreign currency exchange rates against the U.S. dollar and/or currencies of other countries. Issuers of these securities may be more susceptible to actions of foreign governments, such as nationalization, currency blockage or the imposition of price controls or punitive taxes, each of which could adversely impact the value of these securities. Securities markets in certain countries may be more volatile and/or less liquid than those in the U.S. Investments outside the U.S. may also be subject to different accounting practices and different regulatory, legal and reporting standards and practices, and may be more difficult to value, than those in the U.S. In addition, the value of investments outside the U.S. may be reduced by foreign taxes, including foreign withholding taxes on interest and dividends. Further, there may be increased risks of delayed settlement of securities purchased or sold by the fund. The risks of investing outside the U.S. may be heightened in connection with investments in emerging markets.

Management — The investment adviser to the fund actively manages the fund’s investments. Consequently, the fund is subject to the risk that the methods and analyses, including models, tools and data, employed by the investment adviser in this process may be flawed or incorrect and may not produce the desired results. This could cause the fund to lose value or its investment results to lag relevant benchmarks or other funds with similar objectives.

5. Taxation and distributions

Federal income taxation — The fund complies with the requirements under Subchapter M of the Internal Revenue Code applicable to mutual funds and intends to distribute substantially all of its net taxable income and net capital gains each year. The fund is not subject to income taxes to the extent such distributions are made. Therefore, no federal income tax provision is required.

As of and during the period ended August 31, 2020, the fund did not have a liability for any unrecognized tax benefits. The fund recognizes interest and penalties, if any, related to unrecognized tax benefits as income tax expense in the statement of operations. During the period, the fund did not incur any significant interest or penalties.

The fund’s tax returns are not subject to examination by federal, state and, if applicable, non-U.S. tax authorities after the expiration of each jurisdiction’s statute of limitations, which is generally three years after the date of filing but can be extended in certain jurisdictions.

Non-U.S. taxation — Dividend and interest income are recorded net of non-U.S. taxes paid. The fund may file withholding tax reclaims in certain jurisdictions to recover a portion of amounts previously withheld. As a result of rulings from European courts, the fund filed for additional reclaims related to prior years. These reclaims are recorded when the amount is known and there are no significant uncertainties on collectability. Gains realized by the fund on the sale of securities in certain countries, if any, may be subject to non-U.S. taxes. If applicable, the fund records an estimated deferred tax liability based on unrealized gains to provide for potential non-U.S. taxes payable upon the sale of these securities.

Distributions — Distributions paid to shareholders are based on net investment income and net realized gains determined on a tax basis, which may differ from net investment income and net realized gains for financial reporting purposes. These differences are due primarily to different treatment for items such as currency gains and losses; short-term capital gains and losses; capital losses related to sales of certain securities within 30 days of purchase; cost of investments sold and income on certain investments. The fiscal year in which amounts are distributed may differ from the year in which the net investment income and net realized gains are recorded by the fund for financial reporting purposes.

The components of distributable earnings on a tax basis are reported as of the fund’s most recent year-end. As of February 29, 2020, the components of distributable earnings on a tax basis were as follows (dollars in thousands):

As of August 31, 2020, the tax basis unrealized appreciation (depreciation) and cost of investments were as follows (dollars in thousands):

Distributions paid were characterized for tax purposes as follows (dollars in thousands):

6. Fees and transactions with related parties

CRMC, the fund’s investment adviser, is the parent company of American Funds Distributors^®, Inc. (“AFD”), the principal underwriter of the fund’s shares, and American Funds Service Company^® (“AFS”), the fund’s transfer agent. CRMC, AFD and AFS are considered related parties to the fund.

Investment advisory services — The fund has an investment advisory and service agreement with CRMC that provides for monthly fees accrued daily. These fees are based on a series of decreasing annual rates beginning with 0.485% on the first $1 billion of daily net assets and decreasing to 0.277% on such assets in excess of $71 billion. For the six months ended August 31, 2020, the investment advisory services fee was $99,513,000, which was equivalent to an annualized rate of 0.298% of average daily net assets.

Class-specific fees and expenses — Expenses that are specific to individual share classes are accrued directly to the respective share class. The principal class-specific fees and expenses are further described below:

Distribution services — The fund has plans of distribution for all share classes, except Class F-2, F-3, R-5E, R-5 and R-6 shares. Under the plans, the board of trustees approves certain categories of expenses that are used to finance activities primarily intended to sell fund shares and service existing accounts. The plans provide for payments, based on an annualized percentage of average daily net assets, ranging from 0.25% to 1.00% as noted in this section. In some cases, the board of trustees has limited the amounts that may be paid to less than the maximum allowed by the plans. All share classes with a plan may use up to 0.25% of average daily net assets to pay service fees, or to compensate AFD for paying service fees, to firms that have entered into agreements with AFD to provide certain shareholder services. The remaining amounts available to be paid under each plan are paid to dealers to compensate them for their sales activities.

For Class A and 529-A shares, distribution-related expenses include the reimbursement of dealer and wholesaler commissions paid by AFD for certain shares sold without a sales charge. These share classes reimburse AFD for amounts billed within the prior 15 months but only to the extent that the overall annual expense limits are not exceeded. As of August 31, 2020, there were no unreimbursed expenses subject to reimbursement for Class A or 529-A shares.

Transfer agent services — The fund has a shareholder services agreement with AFS under which the fund compensates AFS for providing transfer agent services to each of the fund’s share classes. These services include recordkeeping, shareholder communications and transaction processing. In addition, the fund reimburses AFS for amounts paid to third parties for performing transfer agent services on behalf of fund shareholders.

Administrative services — The fund has an administrative services agreement with CRMC under which the fund compensates CRMC for providing administrative services to all share classes. Administrative services are provided by CRMC and its affiliates to help assist third parties providing non-distribution services to fund shareholders. These services include providing in-depth information on the fund and market developments that impact fund investments. Administrative services also include, but are not limited to, coordinating, monitoring and overseeing third parties that provide services to fund shareholders. The agreement provides the fund the ability to charge an administrative services fee at the annual rate of 0.05% of the daily net assets attributable to each share class of the fund. Currently the fund pays CRMC an administrative services fee at the annual rate of 0.03% of daily net assets attributable to each share class of the fund for CRMC’s provision of administrative services.

529 plan services — Each 529 share class is subject to service fees to compensate the Virginia College Savings Plan (“Virginia529”) for its oversight and administration of the CollegeAmerica 529 college savings plan. The fee is based on the combined net assets invested in Class 529 and ABLE shares of the American Funds. Class ABLE shares are offered on other American Funds by Virginia529 through ABLEAmerica^®, a tax-advantaged savings program for individuals with disabilities. The quarterly fee is based on a series of decreasing annual rates beginning with 0.09% on the first $20 billion of the combined net assets invested in the American Funds and decreasing to 0.03% on such assets in excess of $100 billion. The fee for any given calendar quarter is accrued and calculated on the basis of the average net assets of Class 529 and ABLE shares of the American Funds for the last month of the prior calendar quarter. The fee is included in other expenses in the fund’s statement of operations. Virginia529 is not considered a related party to the fund.

For the six months ended August 31, 2020, class-specific expenses under the agreements were as follows (dollars in thousands):

Trustees’ deferred compensation — Trustees who are unaffiliated with CRMC may elect to defer the cash payment of part or all of their compensation. These deferred amounts, which remain as liabilities of the fund, are treated as if invested in shares of the fund or other American Funds. These amounts represent general, unsecured liabilities of the fund and vary according to the total returns of the selected funds. Trustees’ compensation of $280,000 in the fund’s statement of operations reflects $216,000 in current fees (either paid in cash or deferred) and a net increase of $64,000 in the value of the deferred amounts.

Affiliated officers and trustees — Officers and certain trustees of the fund are or may be considered to be affiliated with CRMC, AFD and AFS. No affiliated officers or trustees received any compensation directly from the fund.

Investment in CCF — The fund holds shares of CCF, an institutional prime money market fund managed by CRMC. CCF invests in high-quality, short-term money market instruments. CCF is used as the primary investment vehicle for the fund’s short-term investments. CCF shares are only available for purchase by CRMC, its affiliates, and other funds managed by CRMC or its affiliates, and are not available to the public. CRMC does not receive an investment advisory services fee from CCF.

Security transactions with related funds — The fund purchased securities from, and sold securities to, other funds managed by CRMC (or funds managed by certain affiliates of CRMC) under procedures adopted by the fund’s board of trustees. The funds involved in such transactions are considered related by virtue of having a common investment adviser (or affiliated investment advisers), common trustees and/or common officers. Each transaction was executed at the current market price of the security and no brokerage commissions or fees were paid in accordance with Rule 17a-7 of the 1940 Act. During the six months ended August 31, 2020, the fund engaged in such purchase and sale transactions with related funds in the amounts of $647,292,000 and $413,222,000, respectively, which generated $46,294,000 of net realized losses from such sales.

Interfund lending — Pursuant to an exemptive order issued by the SEC, the fund, along with other CRMC-managed funds (or funds managed by certain affiliates of CRMC), may participate in an interfund lending program. The program provides an alternate credit facility that permits the funds to lend or borrow cash for temporary purposes directly to or from one another, subject to the conditions of the exemptive order. The fund did not lend or borrow cash through the interfund lending program at any time during the six months ended August 31, 2020.

7. Capital share transactions

Capital share transactions in the fund were as follows (dollars and shares in thousands):

8. Investment transactions

The fund made purchases and sales of investment securities, excluding short-term securities and U.S. government obligations, if any, of $9,759,693,000 and $10,770,168,000, respectively, during the six months ended August 31, 2020.

Financial highlights