Item 1. Report to Stockholders:
The following is a copy of the report transmitted to stockholders pursuant to Rule 30e-1 under the Investment Company Act of 1940:

Putnam
High Income
Securities Fund

Semiannual report
2 | 28 | 11

Message from the Trustees

Dear Fellow Shareholder:

The U.S. economy and stock market continue to show resilience, even in the face of rising head winds around the globe. On March 9, 2011, U.S. equities marked the two-year anniversary of the beginning of the most powerful bull market since the 1950s, with the S&P 500 Index doubling from its 2009 low.

While Putnam maintains a positive outlook for U.S. equities and the overall economy in 2011, we believe volatility will punctuate the year ahead. Civil unrest in the Middle East and North Africa, high unemployment, rising oil prices, and Japan’s earthquake, tsunami, and nuclear crisis have all created a climate of uncertainty. In addition, the U.S. fixed-income market continues to struggle, as yields have risen and bond prices have fallen. We believe that Putnam’s active, research-intensive approach is well suited to uncovering opportunities in this environment.

In developments affecting oversight of your fund, we wish to thank Richard B. Worley and Myra R. Drucker, who have retired from the Board of Trustees, for their many years of dedicated and thoughtful leadership.

Lastly, we would like to take this opportunity to welcome new shareholders to the fund and to thank all of our investors for your continued confidence in Putnam.

About the fund

Seeking opportunities from high-yield bonds and convertibles

The average investor may think of bonds as government-sponsored securities that offer relatively low risk and less volatility than the stock market. However, high-yield corporate bonds and convertible securities, the types of investments primarily held by Putnam High Income Securities Fund, are different. Both are issued by companies rather than the government. Moreover, high-yield corporates and convertibles can offer greater returns than other bonds — but also carry a greater potential for risk, such as the risk of corporate default or periodic illiquidity.

High-yield bonds are deemed to be less than investment-grade status, which means their issuing companies are considered more likely to default on their loans than more credit-worthy counterparts. High-yield bond prices tend to follow individual companies’ fundamentals as well as interest-rate levels. While lower-rated corporate bonds may carry higher risk, they provide potentially higher levels of yield to compensate investors for that risk.

What sets convertible securities apart is a unique built-in option that allows the investor to exchange — or convert — the security for a fixed number of shares of common stock of the issuer. Like most bonds, convertible securities pay interest, although frequently at a lower rate, and the amount of interest does not change as the price of the underlying stock(s) increases or decreases. Issuers can include large, well-known S&P 500 corporations; small, rapidly growing companies; or businesses in cyclically depressed areas such as the automotive industry in 2009.

Building a portfolio of high-yield bonds and convertible securities with the appropriate balance of risk and return potential requires intensive research and analysis. Putnam’s global equity and credit research analysts conduct rigorous research in an effort to determine the true worth of the issuing company’s business. The fund’s portfolio managers then construct a portfolio that they believe offers the best return potential without undue risk.

Consider these risks before investing: Lower-rated bonds may offer higher yields in return for more risk. Funds that invest in bonds are subject to certain risks, including interest-rate risk, credit risk, and inflation risk. As interest rates rise, the prices of bonds fall. Long-term bonds are more exposed to interest-rate risk than short-term bonds. Unlike bonds, bond funds have ongoing fees and expenses. The fund’s shares trade on a stock exchange at market prices, which may be lower than the fund’s net asset value.

How do closed-end funds differ from open-end funds?

More assets at work While open-end funds need to maintain a cash position to meet redemptions, closed-end funds are not subject to redemptions and can keep more of their assets invested in the market.

Traded like stocks Closed-end fund shares are traded on stock exchanges, and their market prices fluctuate in response to supply and demand, among other factors.

Net asset value vs. market price Like an open-end fund’s net asset value (NAV) per share, the NAV of a closed-end fund share is equal to the current value of the fund’s assets, minus its liabilities, divided by the number of shares outstanding. However, when buying or selling closed-end fund shares, the price you pay or receive is the market price. Market price reflects current market supply and demand, and may be higher or lower than the NAV.

Data are historical. Past performance does not guarantee future results. More recent returns may be less or more than those shown. Investment return and net asset value will fluctuate, and you may have a gain or a loss when you sell your shares. Performance assumes reinvestment of distributions and does not account for taxes. Fund returns in the bar chart are at NAV. See pages 5 and 11–12 for additional performance information, including fund returns at market price. Index and Lipper results should be compared to fund performance at NAV. Lipper calculates performance differently than the closed-end funds it ranks, due to varying methods for determining a fund’s monthly reinvestment NAV.

* The fund’s benchmarks, the BofA Merrill Lynch All-Convertibles Speculative Quality Index and the JPMorgan Developed High Yield Index, were introduced on 12/31/92 and 12/31/94, respectively, which post-date the inception of the fund.

† Returns for the six-month period are not annualized, but cumulative.

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Interview with your fund’s portfolio managers

Eric Harthun and Robert Salvin

How did the fund perform for the six months ended February 28, 2011?

Rob: Putnam High Income Securities Fund returned 15.27% at net asset value, underperforming both its primary benchmark, the BofA Merrill Lynch All-Convertibles Speculative Quality Index, which advanced 23.48%, and the average return of its Lipper peer group, Convertible Securities Funds [closed-end], which finished at 18.27%. During the same period, the fund’s secondary benchmark, the JPMorgan Developed High Yield Index, gained 10.20%.

How would you characterize the market environment for high-yield convertibles and bonds during this period?

Eric: As hybrid securities, convertibles are affected by trends in both the equity and credit markets. Similarly, high-yield bonds are influenced by credit-market conditions, and also by expectations for economic growth and corporate profitability. During the past six months, as the U.S. economy showed renewed signs of vigor, and total corporate profits eclipsed their pre-recession peak, stocks registered very strong returns, and credit market conditions remained supportive. As a result, high-yield convertibles and bonds outperformed other fixed-income categories by substantial margins. In fact, the performance of high-yield convertibles was on par with that of many equity-market segments.

Rob: In the high-yield bond market specifically, the record pace of new-issuance witnessed in 2010 continued into the early months of 2011. As U.S. corporations achieved robust earnings, and access to capital became easier and cheaper, companies’ refinanced existing debt and strengthened their balance sheets, thereby reducing the risk of default.

This comparison shows your fund’s performance in the context of broad market indexes for the six months ended 2/28/11. See pages 4 and 11–12 for additional fund performance information. Index descriptions can be found on page 13.

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The high-yield bond default rate declined from nearly 14% at the end of 2009 to low single-digit levels by the end of the period, moving well below historical averages.

Why did the fund underperform its primary benchmark?

Eric: From a sector perspective, on the high-yield convertibles side of the fund, adverse security selection in consumer cyclicals and weak positioning in communication services, financials, and energy more than offset positive contributions from transportation, consumer staples, and basic materials. In addition, the fund’s bias toward somewhat higher-quality high-yield convertibles and bonds hurt results in a market that was led by lower-rated, more-speculative issuers. Lastly, while high-yield bonds performed well, they underperformed high-yield convertibles. Consequently, the fund’s approximately 40% allocation to high-yield bonds dampened its total return.

Which holdings were the primary detractors?

Eric: A key aspect of our investment strategy is to seek to control the fund’s risk by keeping the portfolio broadly diversified. This approach typically prevents us from taking index-sized positions in many of the primary benchmark’s largest constituents. As a result, an underweighted position in Ford Motor, which we view positively and which performed well, was the biggest individual detractor. Ford’s convertibles are heavily represented in the index, and the fund was hurt by its underweighted exposure during the time the company’s convertibles increased the most.

An out-of-benchmark investment in General Motors [GM] proved disappointing. We participated in GM’s initial public offering in late 2010, believing the convertibles — which were issued concurrently with its new common stock — represented an attractive opportunity. However, when GM announced

Credit qualities are shown as a percentage of net assets as of 2/28/11. A bond rated Baa or higher (Prime-3 or higher, for short-term debt) is considered investment grade. The chart reflects Moody’s ratings; percentages may include bonds or derivatives not rated by Moody’s but rated by Standard & Poor’s (S&P) or, if unrated by S&P, by Fitch, and then included in the closest equivalent Moody’s rating. Ratings will vary over time.

Derivative instruments, including currency forwards, are only included to the extent of any unrealized gain or loss on such instruments and are shown in the not-rated category. The fund itself has not been rated by an independent rating agency.

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lower-than-expected quarterly earnings in February 2011, the prices of both its common shares and convertibles declined.

Insurance underwriter Old Republic International — also not in the benchmark — was another detractor. Faced with a challenging environment for its core businesses, especially mortgage insurance, Old Republic’s earnings were volatile during the period, and its securities underperformed as a result.

Two out-of-index holdings listed among the fund’s detractors actually performed quite well but trailed the fund’s primary benchmark from the time we initially invested to the end of the period. These were wireless communication company Crown Castle International and mobile telephony provider NII Holdings, which has a strong presence in Latin America.

Rob: Among individual high-yield bond positions, the primary detractors were real estate brokerage and franchising operator Realogy, whose brands include CENTURY 21 and Coldwell Banker; advertising agency Vertis; and magazine publisher American Media.

Which investments were the biggest contributors to relative performance?

Eric: The top overall contributors were two out-of-benchmark positions: Safeguard Scientifics, which is a private equity and venture capital firm specializing in expansion financing for technology companies, and Retail Ventures, which operates DSW and Value City retail stores. Safeguard began to reap the benefits from many of the companies it has helped finance, and the cash

The table shows the fund’s top 10 individual holdings and the percentage of the fund’s net assets that each represented as of 2/28/11. Short-term holdings are excluded. Holdings will vary over time.

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flows it received from its investments boosted the company’s credit profile and its securities. In the case of Retail Ventures, the company is a relatively small retailer with significant debt on its balance sheet. Its securities were severely punished during the credit crisis and recession before rebounding sharply as the equity and convertibles markets recovered.

Underweighting underperforming telecommunication services provider Equinix also helped, as the company issued disappointing revenue guidance and a profit warning in October, and the prices of its convertibles fell precipitously.

A greater-than-benchmark stake in General Cable was another leading contributor. The company makes copper, aluminum, and fiber optic wire and cable products, and has benefited from increased demand from the communication distribution/transmission and construction industries amid the global economic recovery.

An overweight in FelCor Lodging Trust, which is one of the largest hotel real estate investment trusts in the United States, also boosted results. FelCor Lodging runs hotels in the United States and Canada. Its properties are positioned in the “upscale” and “upper-upscale” segments, and include such brands as Holiday Inn, Doubletree, Sheraton, Embassy Suites, and Westin. The company substantially recapitalized its balance sheet, and despite pressure on average room rates, benefited from increases in both business and leisure travel.

Rob: Top individual contributors among the fund’s high-yield bond holdings included semiconductor maker Freescale Semiconductor, satellite provider Intelsat Bermuda [now known as Intelsat Luxembourg], and airbag maker and safety-parts supplier TRW Automotive.

This chart shows how the fund’s weightings have changed over the past six months. Weightings are shown as a percentage of net assets. Summary information may differ from the portfolio schedule included in the financial statements due to the inclusion of derivative securities and the exclusion of as-of trades, if any, and the use of different classifications of securities for presentation purposes. Holdings will vary over time.

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What is your outlook for the economy and the high-yield convertible and bond markets over the coming months?

Eric: We evaluate the convertibles market by looking at three key factors: fundamentals, valuation, and “technicals,” or the balance of supply and demand. As of now, we have a positive view of all three factors.

Looking first at fundamentals, while the U.S. stock market advanced sharply during the period, we believe stocks’ upward momentum may continue, given increasing signs of a strengthening economy. This is not to say there are no clouds on the horizon. Unrest in the Middle East has driven oil prices above $100 per barrel. If oil prices continue to move higher, this could severely dampen U.S. growth prospects.

Regarding valuation, during the period, convertible valuations moved back toward more normal levels versus their historical average. As a result, in our view, convertible valuations are once again statistically attractive.

As for technicals, convertible new-issue volume has been below historical averages, with investment-grade and high-yield bonds garnering the lion’s share of new issuance. However, as 2011 progresses, we believe interest rates will continue to rise as the economy strengthens, which would likely boost issuance of new convertibles. In our view, this would be a positive development for the market, as increased supply would likely be met by firm demand.

Rob: In the high-yield bond market, we believe defaults are likely to remain low, and, all told, the fundamentals driving the corporate bond market appear quite positive. In addition, the sector has attracted a significant amount of capital flows, creating a very supportive technical environment.

Thanks for updating us, gentlemen.

The views expressed in this report are exclusively those of Putnam Management. They are not meant as investment advice.

Please note that the holdings discussed in this report may not have been held by the fund for the entire period. Portfolio composition is subject to review in accordance with the fund’s investment strategy and may vary in the future. Current and future portfolio holdings are subject to risk.

Portfolio Manager Eric Harthun has an M.B.A. from The University of Chicago Booth School of Business and a B.S. from San Diego State University. A CFA charterholder, Eric joined Putnam in 2000 and has been in the investment industry since 1994.

Portfolio Manager Robert Salvin has an M.B.A. from The University of Chicago Booth School of Business and a B.S. from the Wharton School of the University of Pennsylvania. He joined Putnam in 2000 and has been in the investment industry since 1986.

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IN THE NEWS

The Federal Reserve continues to back its stimulus efforts already under way. Besides maintaining its near-zero interest-rate policy, the Federal Open Market Committee at its March 15 meeting remained committed to completing its second round of quantitative easing, dubbed “QE2.” The central bank launched QE2, which involves the purchase of $600 billion in U.S. Treasury securities, last fall with the primary aim of preventing deflation in the U.S. economy. Last summer, the United States teetered perilously on the verge of a deflationary cliff, as inflation rates had fallen to 50-year lows. Deflation, which occurs when prices fall in an economy, can cause long-term significant damage to growth. QE2 may have worked, as inflation is back. In January, prices measured by the Consumer Price Index (CPI) were up 1.6% from a year earlier, the biggest increase in eight months. Core inflation rose by 0.5%, the highest increase since October 2008.

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Your fund’s performance

This section shows your fund’s performance, price, and distribution information for periods ended February 28, 2011, the end of the first half of its current fiscal year. In accordance with regulatory requirements for mutual funds, we also include performance as of the most recent calendar quarter-end. Performance should always be considered in light of a fund’s investment strategy. Data represent past performance. Past performance does not guarantee future results. More recent returns may be less or more than those shown. Investment return, net asset value, and market price will fluctuate, and you may have a gain or a loss when you sell your shares.

Fund performance Total return for periods ended 2/28/11

Performance assumes reinvestment of distributions and does not account for taxes.

Comparative index returns For periods ended 2/28/11

Index and Lipper results should be compared to fund performance at net asset value. Lipper calculates performance differently than the closed-end funds it ranks, due to varying methods for determining a fund’s monthly reinvestment NAV.

* The fund’s benchmarks, the BofA Merrill Lynch All-Convertibles Speculative Quality Index and the JPMorgan Developed High Yield Index, were introduced on 12/31/92 and 12/31/94, respectively, which post-date the inception of the fund.

† Over the 6-month, 1-year, 3-year, 5-year, 10-year, and life-of-fund periods ended 2/28/11, there were 11, 11, 11, 9, 4, and 2 funds, respectively, in this Lipper category.

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Fund price and distribution information For the six-month period ended 2/28/11

The classification of distributions, if any, is an estimate. Final distribution information will appear on your year-end tax forms.

* Most recent distribution, excluding capital gains, annualized and divided by NAV or market price at end of period.

Fund performance as of most recent calendar quarter
Total return for periods ended 3/31/11

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Terms and definitions

Important terms

Total return shows how the value of the fund’s shares changed over time, assuming you held the shares through the entire period and reinvested all distributions in the fund.

Net asset value (NAV) is the value of all your fund’s assets, minus any liabilities, divided by the number of outstanding shares.

Market price is the current trading price of one share of the fund. Market prices are set by transactions between buyers and sellers on exchanges such as the New York Stock Exchange.

Current yield is the annual rate of return earned from dividends or interest of an investment. Current yield is expressed as a percentage of the price of a security, fund share, or principal investment.

Comparative indexes

Barclays Capital Aggregate Bond Index is an unmanaged index of U.S. investment-grade fixed-income securities.

BofA (Bank of America) Merrill Lynch All-Convertibles Speculative Quality Index is an unmanaged index of U.S. convertible securities.

BofA (Bank of America) Merrill Lynch U.S. 3-Month Treasury Bill Index is an unmanaged index that seeks to measure the performance of U.S. Treasury bills available in the marketplace.

JPMorgan Developed High Yield Index is an unmanaged index of high-yield fixed-income securities issued in developed countries.

S&P 500 Index is an unmanaged index of common stock performance.

Indexes assume reinvestment of all distributions and do not account for fees. Securities and performance of a fund and an index will differ. You cannot invest directly in an index.

Lipper is a third-party industry-ranking entity that ranks mutual funds. Its rankings do not reflect sales charges. Lipper rankings are based on total return at net asset value relative to other funds that have similar current investment styles or objectives as determined by Lipper. Lipper may change a fund’s category assignment at its discretion. Lipper category averages reflect performance trends for funds within a category.

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Other information for shareholders

Important notice regarding share repurchase program

In September 2010, the Trustees of your fund approved the renewal of a share repurchase program that had been in effect since 2005. This renewal will allow your fund to repurchase, in the 12 months beginning October 8, 2010, up to 10% of the fund’s common shares outstanding as of October 7, 2010.

Important notice regarding delivery of shareholder documents

In accordance with SEC regulations, Putnam sends a single copy of annual and semiannual shareholder reports, prospectuses, and proxy statements to Putnam shareholders who share the same address, unless a shareholder requests otherwise. If you prefer to receive your own copy of these documents, please call Putnam at 1-800-225-1581, and Putnam will begin sending individual copies within 30 days.

Proxy voting

Putnam is committed to managing our mutual funds in the best interests of our shareholders. The Putnam funds’ proxy voting guidelines and procedures, as well as information regarding how your fund voted proxies relating to portfolio securities during the 12-month period ended June 30, 2010, are available in the Individual Investors section of putnam.com, and on the SEC’s website, www.sec.gov. If you have questions about finding forms on the SEC’s website, you may call the SEC at 1-800-SEC-0330. You may also obtain the Putnam funds’ proxy voting guidelines and procedures at no charge by calling Putnam’s Shareholder Services at 1-800-225-1581.

Fund portfolio holdings

The fund will file a complete schedule of its portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. Shareholders may obtain the fund’s Forms N-Q on the SEC’s website at www.sec.gov. In addition, the fund’s Forms N-Q may be reviewed and copied at the SEC’s Public Reference Room in Washington, D.C. You may call the SEC at 1-800-SEC-0330 for information about the SEC’s website or the operation of the Public Reference Room.

Trustee and employee fund ownership

Putnam employees and members of the Board of Trustees place their faith, confidence, and, most importantly, investment dollars in Putnam mutual funds. As of February 28, 2011, Putnam employees had approximately $372,000,000 and the Trustees had approximately $69,000,000 invested in Putnam mutual funds. These amounts include investments by the Trustees’ and employees’ immediate family members as well as investments through retirement and deferred compensation plans.

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Financial statements

A guide to financial statements

These sections of the report, as well as the accompanying Notes, constitute the fund’s financial statements.

The fund’s portfolio lists all the fund’s investments and their values as of the last day of the reporting period. Holdings are organized by asset type and industry sector, country, or state to show areas of concentration and diversification.

Statement of assets and liabilities shows how the fund’s net assets and share price are determined. All investment and non-investment assets are added together. Any unpaid expenses and other liabilities are subtracted from this total. The result is divided by the number of shares to determine the net asset value per share. (For funds with preferred shares, the amount subtracted from total assets includes the liquidation preference of preferred shares.)

Statement of operations shows the fund’s net investment gain or loss. This is done by first adding up all the fund’s earnings — from dividends and interest income — and subtracting its operating expenses to determine net investment income (or loss). Then, any net gain or loss the fund realized on the sales of its holdings — as well as any unrealized gains or losses over the period — is added to or subtracted from the net investment result to determine the fund’s net gain or loss for the fiscal period.

Statement of changes in net assets shows how the fund’s net assets were affected by the fund’s net investment gain or loss, by distributions to shareholders, and by changes in the number of the fund’s shares. It lists distributions and their sources (net investment income or realized capital gains) over the current reporting period and the most recent fiscal year-end. The distributions listed here may not match the sources listed in the Statement of operations because the distributions are determined on a tax basis and may be paid in a different period from the one in which they were earned. Dividend sources are estimated at the time of declaration. Actual results may vary. Any non-taxable return of capital cannot be determined until final tax calculations are completed after the end of the fund’s fiscal year.

Financial highlights provide an overview of the fund’s investment results, per-share distributions, expense ratios, net investment income ratios, and portfolio turnover in one summary table, reflecting the five most recent reporting periods. In a semiannual report, the highlights table also includes the current reporting period.

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The fund’s portfolio 2/28/11 (Unaudited)

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