Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus, statement of additional information, reports to shareholders and other information about the Fund online at www.franklintempleton.com/prospectus. You can also get this information at no cost by calling (800) DIAL BEN/342-5236 or by sending an e-mail request to prospectus@franklintempleton.com. The Fund’s prospectus and statement of additional information, both dated February 1, 2024, as may be supplemented, are all incorporated by reference into this Summary Prospectus.

FRANKLIN HIGH INCOME FUND
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Fund Summary

Investment Goals

To earn a high level of current income. Its secondary goal is to seek capital appreciation to the extent it is possible and consistent with the Fund's principal goal.

Fees and Expenses of the Fund

These tables describe the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees (including on Class R6 and Advisor Class shares), such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts in Class A if you and your family invest, or agree to invest in the future, at least $100,000 in Franklin Templeton funds and certain other funds distributed through Franklin Distributors, LLC, the Fund’s distributor. More information about these and other discounts is available from your financial professional and under “Your Account” on page 40 in the Fund’s Prospectus and under “Buying and Selling Shares” on page 64 of the Fund’s Statement of Additional Information. In addition, more information about sales charge discounts and waivers for purchases of shares through specific financial intermediaries is set forth in Appendix A – “Intermediary Sales Charge Discounts and Waivers” to the Fund’s prospectus.

Shareholder Fees

(fees paid directly from your investment)

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Annual Fund Operating Expenses

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

^1. Total annual Fund operating expenses differ from the ratio of expenses to average net assets shown in the Financial Highlights, which reflect the operating expenses of the Fund and do not include acquired fund fees and expenses.

^2. The investment manager has agreed to reduce its fees to reflect reduced services resulting from the Fund’s investments in Franklin Templeton affiliated funds. In addition, the transfer agency fees on Class R6 shares of the Fund have been capped so that transfer agency fees for that class do not exceed 0.03%. These arrangements are expected to continue until January 31, 2025. During the terms, the fee waiver and expense reimbursement agreements may not be terminated or amended without approval of the board of trustees except to add series or classes, to reflect the extension of termination dates or to lower the waiver and expense limitation (which would result in lower fees for shareholders).

Example

This 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 in the Fund for the time periods indicated and then redeem all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The Example reflects adjustments made to the Fund's operating expenses due to the fee waivers and/or expense reimbursements by management for the 1 Year numbers only. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

FRANKLIN HIGH INCOME FUND
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Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in 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 34.60% of the average value of its portfolio.

Principal Investment Strategies

Under normal market conditions, the Fund invests predominantly in high yield, lower-rated debt securities. Lower-rated securities generally pay higher yields than more highly rated securities to compensate investors for the higher risk. These securities include bonds, notes, debentures, convertible securities and senior and subordinated debt securities. The Fund may also invest in preferred stock.

The Fund may invest up to 100% of its total assets in debt securities that are rated below investment grade, also known as “junk bonds.” Investment grade debt securities are rated in one of the top four ratings categories by at least one independent rating agency such as S&P ^® Global Ratings (S&P ^®) and Moody’s Investors Service (Moody’s). The Fund may buy both rated and unrated debt securities, including securities rated below B by Moody's or S&P ^® (or deemed comparable by the Fund's investment manager). The Fund may also invest in defaulted debt securities and in securities issued by issuers in any foreign country, developed or developing. Foreign securities held by the Fund generally will be denominated in U.S. dollars and traded on U.S. markets.

The Fund's investment manager is a research driven, fundamental investor that relies on a team of analysts to provide in-depth industry expertise and uses both qualitative and quantitative analysis to evaluate issuers. As a "bottom-up" investor, the investment manager focuses primarily on individual securities. The investment manager also considers sectors when choosing investments and, from time to time, may have significant investments in certain sectors.

In selecting securities for the Fund’s investment portfolio, the investment manager does not rely principally on the ratings assigned by rating agencies, but performs its own independent investment analysis to evaluate the creditworthiness of the issuer. The investment manager considers a variety of factors, including the issuer’s experience and managerial strength, its sensitivity to economic conditions, and its current and prospective financial condition.

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Principal Risks

You could lose money by investing in the Fund. Mutual fund shares are not deposits or obligations of, or guaranteed or endorsed by, any bank, and are not insured by the Federal Deposit Insurance Corporation, the Federal Reserve Board, or any other agency of the U.S. government.

Credit: An issuer of debt securities may fail to make interest payments or repay principal when due, in whole or in part. Changes in an issuer's financial strength or in a security's or government's credit rating may affect a security's value.

High-Yield Debt Securities: Issuers of lower-rated or “high-yield” debt securities (also known as “junk bonds”) are not as strong financially as those issuing higher credit quality debt securities. High-yield debt securities are generally considered predominantly speculative by the applicable rating agencies as their issuers are more likely to encounter financial difficulties because they may be more highly leveraged, or because of other considerations. In addition, high yield debt securities generally are more vulnerable to changes in the relevant economy, such as a recession or a sustained period of rising interest rates, that could affect their ability to make interest and principal payments when due. The prices of high-yield debt securities generally fluctuate more than those of higher credit quality. High-yield debt securities are generally more illiquid (harder to sell) and harder to value.

Interest Rate: When interest rates rise, debt security prices generally fall. The opposite is also generally true: debt security prices rise when interest rates fall. Interest rate changes are influenced by a number of factors, including government policy, monetary policy, inflation expectations, perceptions of risk, and supply of and demand for bonds. In general, securities with longer maturities or durations are more sensitive to interest rate changes.

Income: The Fund's distributions to shareholders may decline when prevailing interest rates fall, when the Fund experiences defaults on debt securities it holds or when the Fund realizes a loss upon the sale of a debt security.

Liquidity: The trading market for a particular security or type of security or other investments in which the Fund invests may become less liquid or even illiquid. Reduced liquidity will have an adverse impact on the Fund’s ability to sell such securities or other investments when necessary to meet the Fund’s liquidity needs, which may arise or increase in response to a specific economic event or because the investment manager wishes to purchase particular investments or believes that a higher level of liquidity would be advantageous. Reduced liquidity will also generally lower the value of such securities or other investments. Market prices for such securities or other investments may be relatively volatile.

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Foreign Securities (non-U.S.): Investing in foreign securities typically involves more risks than investing in U.S. securities, and includes risks associated with: (i) internal and external political and economic developments – e.g., the political, economic and social policies and structures of some foreign countries may be less stable and more volatile than those in the U.S. or some foreign countries may be subject to trading restrictions or economic sanctions; diplomatic and political developments could affect the economies, industries, and securities and currency markets of the countries in which the Fund is invested, which can include rapid and adverse political changes; social instability; regional conflicts; sanctions imposed by the United States, other nations or other governmental entities, including supranational entities; terrorism; and war; (ii) trading practices – e.g., government supervision and regulation of foreign securities and currency markets, trading systems and brokers may be less than in the U.S.; (iii) availability of information – e.g., foreign issuers may not be subject to the same disclosure, accounting and financial reporting standards and practices as U.S. issuers; (iv) limited markets – e.g., the securities of certain foreign issuers may be less liquid (harder to sell) and more volatile; and (v) currency exchange rate fluctuations and policies – e.g., fluctuations may negatively affect investments denominated in foreign currencies and any income received or expenses paid by the Fund in that foreign currency. The risks of foreign investments may be greater in developing or emerging market countries.

Focus: To the extent that the Fund focuses on particular countries, regions, industries, sectors or types of investments from time to time, the Fund may be subject to greater risks of adverse developments in such areas of focus than a fund that invests in a wider variety of countries, regions, industries, sectors or investments.

Prepayment: Prepayment risk occurs when a debt security can be repaid in whole or in part prior to the security's maturity and the Fund must reinvest the proceeds it receives, during periods of declining interest rates, in securities that pay a lower rate of interest. Also, if a security has been purchased at a premium, the value of the premium would be lost in the event of prepayment. Prepayments generally increase when interest rates fall.

Market: The market values of securities or other investments owned by the Fund will go up or down, sometimes rapidly or unpredictably. The market value of a security or other investment may be reduced by market activity or other results of supply and demand unrelated to the issuer. This is a basic risk associated with all investments. When there are more sellers than buyers, prices tend to fall. Likewise, when there are more buyers than sellers, prices tend to rise.

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The global outbreak of the novel strain of coronavirus, COVID-19 and its subsequent variants, has resulted in market closures and dislocations, extreme volatility, liquidity constraints and increased trading costs. The long-term impact on economies, markets, industries and individual issuers is not known. Some sectors of the economy and individual issuers have experienced or may experience particularly large losses. Periods of extreme volatility in the financial markets; reduced liquidity of many instruments; and disruptions to supply chains, consumer demand and employee availability, may continue for some time.

Management: The Fund is subject to management risk because it is an actively managed investment portfolio. The Fund's investment manager applies investment techniques and risk analyses in making investment decisions for the Fund, but there can be no guarantee that these decisions will produce the desired results.

Cybersecurity: Cybersecurity incidents, both intentional and unintentional, may allow an unauthorized party to gain access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, cause the Fund, the investment manager, and/or their service providers (including, but not limited to, Fund accountants, custodians, sub-custodians, transfer agents and financial intermediaries) to suffer data breaches, data corruption or loss of operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The investment manager has limited ability to prevent or mitigate cybersecurity incidents affecting third party service providers, and such third party service providers may have limited indemnification obligations to the Fund or the investment manager. Cybersecurity incidents may result in financial losses to the Fund and its shareholders, and substantial costs may be incurred in an effort to prevent or mitigate future cybersecurity incidents. Issuers of securities in which the Fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers experience cybersecurity incidents.

Because technology is frequently changing, new ways to carry out cyber attacks are always developing. Therefore, there is a chance that some risks have not been identified or prepared for, or that an attack may not be detected, which puts limitations on the Fund's ability to plan for or respond to a cyber attack. Like other funds and business enterprises, the Fund, the investment manager, and their service providers are subject to the risk of cyber incidents occurring from time to time.

Performance

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund's performance from year to year for Class A shares. The table shows how the Fund's average annual returns

FRANKLIN HIGH INCOME FUND
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for 1 year, 5 years, 10 years or since inception, as applicable, compared with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You can obtain updated performance information at franklintempleton.com or by calling (800) DIAL BEN/342-5236.

Sales charges are not reflected in the bar chart, and if those charges were included, returns would be less than those shown.

Class A Annual Total Returns

FRANKLIN HIGH INCOME FUND
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Average Annual Total Returns

(figures reflect sales charges)

For periods ended December 31, 2023

No one index is representative of the Fund's portfolio.

The figures in the average annual total returns table above reflect the Class A and Class A1 shares maximum front-end sales charge of 3.75%. Prior to March 1, 2019, Class A and Class A1 shares were subject to a maximum front-end sales charge of 4.25%. If the prior maximum front-end sales charge of 4.25% was reflected, performance for Class A and Class A1 shares in the average annual total returns table would be lower.

Historical performance for Class A shares in the bar chart and table above prior to their inception is based on the performance of Class A1 shares and has been adjusted to reflect differences in Rule 12b-1 fees between classes.

The after-tax returns presented in the table 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 are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown only for Class A and after-tax returns for other classes will vary.

Investment Manager

Franklin Advisers, Inc. (Advisers or investment manager)

Portfolio Managers

Glenn I. Voyles, CFA
Senior Vice President of Advisers and portfolio manager of the Fund since 2015.

FRANKLIN HIGH INCOME FUND
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Bryant Dieffenbacher, CFA 
Portfolio manager of Advisers and portfolio manager of the Fund since 2020.

S. James McGiveran III, CFA, CPA, FRM 
Portfolio manager of Advisers and portfolio manager of the Fund since 2020.

Patricia O’Connor, CFA
Vice President of Advisers and portfolio manager of the Fund since 2020.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day online through our website at franklintempleton.com, by mail (Franklin Templeton Investor Services, P.O. Box 997152, Sacramento, CA 95899-7152), or by telephone at (800) 632-2301. For Class A, C and R, the minimum initial purchase for most accounts is $1,000 (or $25 under an automatic investment plan). Class R6 and Advisor Class are only available to certain qualified investors and the minimum initial investment will vary depending on the type of qualified investor, as described under "Your Account — Choosing a Share Class — Qualified Investors — Class R6" and "— Advisor Class" in the Fund's prospectus. There is no minimum investment for subsequent purchases.

Taxes

The Fund’s distributions are generally taxable to you as ordinary income, capital gains, or some combination of both, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account, in which case your distributions would generally be taxed when withdrawn from the tax-advantaged account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. 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. Ask your financial advisor or visit your financial intermediary's website for more information.