May 31, 2017

Rydex Series Funds

805 King Farm Blvd., Suite 600

Rockville, Maryland 20850

RYDEX SERIES FUNDS

Guggenheim Long Short Equity Fund

Supplement dated May 31, 2017 to the currently effective Statutory Prospectuses (together, the “Prospectuses”) for the Guggenheim Long Short Equity Fund.

This supplement provides new and additional information beyond that contained in the Prospectuses and should be read in conjunction with the Prospectuses.

At a meeting held on May 25, 2017, the Board of Trustees of Rydex Series Funds (the “Trust”) and Security Investors, LLC (the “Advisor”) determined to revise the principal investment strategies of the Guggenheim Long Short Equity Fund (the “Fund”). Accordingly, effective immediately, the Fund’s current principal investment strategies are deleted and replaced in their entirety with the principal investment strategies set forth below.

In addition to the Fund’s revised principal investment strategies, several other related changes also are implemented effective immediately, each of which is discussed in greater detail below. The changes to the Fund’s principal investment strategies will not affect the Fund’s investment objective or fees and expenses. The Advisor expects the Fund will experience increased portfolio turnover and as a result, incur higher transaction costs and possibly, increased short-term capital gains in connection with the implementation of the Fund’s revised principal investment strategies.

I. Revised Principal Investment Strategies

Effective immediately, the current description of the Fund’s principal investment strategies under the heading “Principal Investment Strategies” in the Fund’s “Fund Summary” section is replaced in its entirety as set forth below.

II. Principal Risks

Effective immediately, the current descriptions of the Fund’s principal risks under the heading “Principal Risks” in the Fund’s “Fund Summary” section are deleted and replaced in their entirety with the risk descriptions set forth below.

III. Revised Comparative Benchmark

For periods after May 31, 2017, the Fund will compare its performance to two new performance benchmarks: the Morningstar Long/Short Equity Category Average and the S&P 500^® Index. The new comparative performance benchmarks will accompany the existing comparative performance benchmarks for the next year.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its objective by investing, under normal market conditions, at least 80% of its assets (net assets plus the amount of borrowings for investment purposes) in long and short positions of domestic equity securities or equity-related instruments, including swaps and other derivatives that provide long or short exposure to domestic equity securities. For purposes of determining compliance with the Fund’s 80% investment policy, equity-related derivatives generally will be valued based on their notional value.

The Fund seeks to achieve its investment objective by constructing portfolios that maintain long positions in instruments that provide exposure to risk factors the Advisor considers to be undervalued by the equity markets and sells short instruments that provide exposure to risk factors the Advisor considers to be overvalued by the equity markets. The Advisor considers both market risk factors generally and risks specific to the companies in which the Fund invests. To construct the portfolios, the Advisor uses fundamentally-based, forward-looking forecasts of equity cash flows to generate return expectations for individual companies. Then, the expected returns for the universe of stocks is further evaluated using quantitative techniques to estimate the market’s implied valuation of broad market risk factors as well as company-specific risks. Finally, the Advisor applies its proprietary evaluation process to buy long those stocks (or derivatives that give exposure to the stocks) that give the portfolio both the broad risk characteristics and company-specific risks that are perceived to be undervalued and sell short those stocks (or derivatives that give exposure to the stocks) with characteristics that are perceived to be overvalued.

The Fund will ordinarily hold simultaneous long and short positions in equity securities or securities markets that provide exposure up to a level equal to 300% of the Fund’s net assets for both the long and short positions. That level of exposure is obtained through derivatives, including swap agreements. At any point in time, the Fund’s portfolio may be significantly net long or net short. The Fund’s overall net exposure will change as market opportunities change.

The Fund invests in equity securities, including small-, mid-, and large-capitalization securities, such as U.S. traded common stocks, American Depositary Receipts (“ADRs”) and other investment companies, but also may invest in derivative instruments which primarily consist of swaps on baskets of selected equity securities, futures contracts, and options on securities, futures contracts, and stock indices. The Fund’s investments in derivatives enable the Fund to pursue its investment objective without investing directly in the securities of companies to which the Fund is seeking exposure. The Fund also may invest in derivatives to hedge or gain leveraged exposure to a particular industry, style or company depending on market conditions.

Investments in derivative instruments, such as futures, options and swap agreements, have the economic effect of creating financial leverage in the Fund’s portfolio because such investments may give rise to losses that exceed the amount the Fund has invested in those instruments. Financial leverage will magnify, sometimes significantly, the Fund’s exposure to any increase or decrease in prices associated with a particular reference asset resulting in increased volatility in the value of the Fund’s portfolio. The value of the Fund’s portfolio is likely to experience greater volatility over short-term periods. While such financial leverage has the potential to produce greater gains, it also may result in greater losses, which in some cases may cause the Fund to liquidate other portfolio investments at a loss to comply with limits on leverage and asset segregation requirements imposed by the Investment Company Act of 1940 or to meet redemption requests. The Fund’s use of derivatives and the leveraged investment exposure created by such use are expected to be significant.

Certain of the Fund’s derivatives investments may be traded in the over-the-counter (“OTC”) market, which generally provides for less transparency than exchange-traded derivative instruments. The Fund also may enter into short sales of broad-based stock indices for hedging purposes in an effort to reduce portfolio risk or volatility. While the Fund anticipates investing in these instruments to seek to achieve its investment objective, the extent of the Fund’s investment in these instruments may vary from day to day depending on a number of different factors, including price, availability, and general market conditions. On a day-to-day basis, the Fund may hold U.S. government securities, short-term, high quality (rated AA or higher) fixed income securities, money market instruments, overnight and fixed-term repurchase agreements, cash and other cash equivalents with maturities of one year or less to collateralize its derivatives positions or for defensive purposes to seek to avoid losses during adverse market conditions. The Fund also may enter into repurchase agreements with counterparties that are deemed to present acceptable credit risks. In an effort to ensure that the Fund is fully invested on a day-to-day basis, the Fund may conduct significant trading activity at or just prior to the close of the U.S. financial markets. The Fund is non-diversified and, therefore, may invest a greater percentage of its assets in a particular issuer in comparison to a diversified fund.

As with all mutual funds, a shareholder is subject to the risk that his or her investment could lose money. In addition to this risk, the Fund is subject to the principal risks described below.

COUNTERPARTY CREDIT RISK—The Fund may invest in financial instruments involving counterparties that attempt to gain exposure to a particular group of securities, index or asset class without actually purchasing those securities or investments, or to hedge a position. The Fund’s use of such financial instruments, including swap agreements, involves risks that are different from those associated with ordinary portfolio securities transactions. For example, the Fund is exposed to the risk that the counterparty may be unwilling or unable to make timely payments to meet its contractual obligations or may fail to return holdings that are subject to the agreement with the counterparty. If the counterparty becomes bankrupt or defaults on its payment obligations to the Fund, the Fund may not receive the full amount that it is entitled to receive. If this occurs, the value of your shares in the Fund will decrease.

DEPOSITARY RECEIPT RISK—The Fund may hold the securities of non-U.S. companies in the form of ADRs. The underlying securities of the ADRs in the Fund’s portfolio are subject to fluctuations in foreign currency exchange rates that may affect the value of the Fund’s portfolio. In addition, the value of the securities underlying the ADRs may change materially when the U.S. markets are not open for trading. Investments in the underlying foreign securities also involve political and economic risks distinct from those associated with investing in the securities of U.S. issuers.

DERIVATIVES RISK—The Fund’s investments in derivatives may pose risks in addition to and greater than those associated with investing directly in securities or other investments, including risks relating to leverage, imperfect correlations with underlying investments or the Fund’s other portfolio holdings, high price volatility, lack of availability, counterparty credit, liquidity, valuation and legal restrictions. Their use is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. If the Advisor is incorrect about its expectations of market conditions, the use of derivatives could also result in a loss, which in some cases may be unlimited. Certain risks are specific to the derivatives in which the Fund invests.

SWAP AGREEMENTS RISK—Swap agreements are contracts among the Fund and a counterparty to exchange the return of the pre-determined underlying investment (such as the rate of return of the underlying index). Swap agreements may be negotiated bilaterally and traded OTC between two parties or, in some instances, must be transacted through a futures commission merchant and cleared through a clearinghouse that serves as a central counterparty. Risks associated with the use of swap agreements are different from those associated with ordinary portfolio securities transactions, due in part to the fact they could be considered illiquid and many swaps trade on the OTC market. Swaps are particularly subject to counterparty credit, correlation, valuation, liquidity and leveraging risks. Certain standardized swaps are subject to mandatory central clearing. Central clearing is expected to reduce counterparty credit risk and increase liquidity, but central clearing does not make swap transactions risk-free.

FUTURES CONTRACTS RISK—Futures contracts are typically exchange-traded contracts that call for the future delivery of an asset at a certain price and date, or cash settlement of the terms of the contract. Risks of futures contracts may be caused by an imperfect correlation between movements in the price of the instruments and the price of the underlying securities. In addition, there is the risk that the Fund may not be able to enter into a closing transaction because of an illiquid market. Exchanges can limit the number of positions that can be held or controlled by the Fund or the Advisor, thus limiting the ability to implement the Fund’s strategies. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s net asset value (“NAV”). Futures are also subject to leverage risks and to liquidity risk.

OPTIONS RISK—Options or options on futures contracts give the holder of the option the right to buy (or to sell) a position in a security or in a contract to the writer of the option, at a certain price. They are subject to correlation risk because there may be an imperfect correlation between the options and the securities markets that cause a given transaction to fail to achieve its objectives. The successful use of options depends on the Advisor’s ability to correctly predict future price fluctuations and the degree of correlation between the options and securities markets. Exchanges can limit the number of positions that can be held or controlled by the Fund or the Advisor, thus limiting the ability to implement the Fund’s strategies. Options are also particularly subject to leverage risk and can be subject to liquidity risk.

EARLY CLOSING RISK—The Fund is subject to the risk that unanticipated early closings of securities exchanges and other financial markets may result in the Fund’s inability to buy or sell securities or other financial instruments on that day and may cause the Fund to incur substantial trading losses.

EQUITY RISK—The Fund is subject to the risk that the value of the equity securities and equity-based derivatives in the Fund’s portfolio will decline due to volatility in the equity market caused by general market and economic conditions, perceptions regarding particular industries represented in the equity market, or factors relating to specific companies to which the Fund has investment exposure.

FINANCIALS SECTOR RISK—The Fund's investments are exposed to issuers conducting business in the Financials Sector. The Financials Sector includes companies involved in banking, thrifts and mortgage finance, specialized finance, consumer finance, asset management and custody banks, investment banking and brokerage and insurance. It also includes Financial Exchanges and Data and Mortgage REITs. Certain financial sector companies serve as counterparties with which the Fund may enter into derivatives agreements or other similar contractual arrangements. The Fund’s exposure to such companies subjects the Fund to the risk that their securities will underperform the market as a whole due to legislative or regulatory changes, adverse market conditions and/or increased competition affecting the Financials Sector, which may adversely affect a company’s ability to fulfill its obligations as a financial counterparty. Companies operating in the Financials Sector are subject to extensive government regulation, which may limit the financial commitments they can make and the interest rates and fees they can charge. Profitability is largely dependent on the availability and cost of capital funds, and can fluctuate significantly when interest rates change or due to increased competition.

INVESTMENT IN INVESTMENT VEHICLES RISK—Investing in other investment vehicles, including exchange-traded funds (“ETFs”), closed-end funds and other mutual funds, subjects the Fund to those risks affecting the investment vehicle, including the possibility that the value of the underlying securities held by the investment vehicle could decrease or the portfolio becomes illiquid. Moreover, the Fund and its shareholders will incur its pro rata share of the underlying vehicles’ expenses, which will reduce the Fund’s performance. In addition, investments in an ETF are subject to, among other risks, the risk that the ETF’s shares may trade at a discount or premium relative to the net asset value of the shares and the listing exchange may halt trading of the ETF’s shares.

LARGE-CAPITALIZATION SECURITIES RISK—The Fund is subject to the risk that large-capitalization stocks may underperform other segments of the equity market or the equity market as a whole. Larger, more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and may not be able to attain the high growth rate of smaller companies, especially during extended periods of economic expansion.

LEVERAGING RISK—The Fund’s investment in derivative instruments generally requires a small investment relative to the amount of investment exposure assumed. As a result, such investments may give rise to losses that exceed the amount invested in those instruments. The cost of investing in such instruments generally increases as interest rates increase, which will lower the Fund’s return.

LIQUIDITY AND VALUATION RISK—In certain circumstances, it may be difficult for the Fund to purchase and sell a particular investment within a reasonable time at a fair price, or the price at which it has been valued by the Advisor for purposes of the Fund’s NAV, causing the Fund to be less liquid. While the Fund intends to invest in liquid securities and financial instruments, under certain market conditions, such as when trading in a particular investment has been halted temporarily by an exchange because the maximum price change of that investment has been realized, it may be difficult or impossible for the Fund to liquidate such investments. In addition, the ability of the Fund to assign an accurate daily value to certain investments may be difficult, and the Advisor may be required to fair value the investments.

MANAGEMENT RISK—The Fund is actively managed, which means that investment decisions are made based on investment views. There is no guarantee that the investment views will produce the desired results or expected returns, causing the Fund to fail to meet its investment objective or underperform its benchmark index or funds with similar investment objectives and strategies. Furthermore, active trading that can accompany active management, also called “high turnover,” may have a negative impact on performance. Active trading may result in higher brokerage costs or mark-up charges, which are ultimately passed on to shareholders of the Fund. Active trading may also result in adverse tax consequences.

MARKET RISK—The market value of the securities and derivatives held by the Fund may fluctuate over time in response to factors affecting individual companies or other factors such as changing economic, political or financial markets.

MID-CAPITALIZATION SECURITIES RISK—The Fund is subject to the risk that medium-capitalization stocks may underperform other segments of the equity market or the equity market as a whole. Securities of medium-capitalization companies may experience more price volatility, greater spreads between their bid and ask prices, lower trading volumes, and cyclical or static growth prospects. Medium-capitalization companies often have limited product lines, markets or financial resources, and may therefore be more vulnerable to adverse developments than larger capitalization companies.

NON-DIVERSIFICATION RISK—The Fund is considered non-diversified and can invest a greater portion of its assets in securities of individual issuers than a diversified fund. As a result, changes in the market value of a single issuer's securities could cause greater fluctuations in the value of Fund shares than would occur in a diversified fund.

OTC TRADING RISK—Certain of the derivatives in which the Fund may invest may be traded (and privately negotiated) in the OTC market. While the OTC derivatives market is the primary trading venue for many derivatives, it is largely unregulated. As a result and similar to other privately negotiated contracts, the Fund is subject to counterparty credit risk with respect to such derivatives contracts.

PORTFOLIO TURNOVER RISK—The Fund’s strategy may frequently involve buying and selling portfolio securities, which may lead to increased costs to the Fund. Portfolio turnover risk may cause the Fund’s performance to be less than you expect.

REPURCHASE AGREEMENTS AND REVERSE REPURCHASE AGREEMENTS RISK—In the event of the insolvency of the counterparty to a repurchase agreement or reverse repurchase agreement, recovery of the repurchase price owed to the Fund or, in the case of a reverse repurchase agreement, the securities sold by the Fund, may be delayed. Because reverse repurchase agreements may be considered to be the practical equivalent of borrowing funds, they constitute a form of leverage. If the Fund reinvests the proceeds of a reverse repurchase agreement at a rate lower than the cost of the agreement, entering into the agreement will lower the Fund’s yield.

SHORT SALE AND SHORT EXPOSURE RISK—Short selling a security involves selling a borrowed security with the expectation that the value of that security will decline, so that the security may be purchased at a lower price when returning the borrowed security. A short exposure through a derivative exposes the Fund to counterparty credit risk and leverage risk. The risk for loss on a short sale or other short exposure is greater than a direct investment in the security itself because the price of the borrowed security may rise, thereby increasing the price at which the security must be purchased. The risk of loss through a short sale or other short exposure may in some cases be theoretically unlimited. Government actions also may affect the Fund’s ability to engage in short selling.

SMALL-CAPITALIZATION SECURITIES RISK—The Fund is subject to the risk that small-capitalization stocks may underperform other segments of the equity market or the equity market as a whole. Small-capitalization companies may be more vulnerable than larger, more established organizations to adverse business or economic developments. Securities of small-capitalization companies may experience much more price volatility, greater spreads between their bid and ask prices, significantly lower trading volumes, and cyclical or static growth prospects. Small-capitalization companies often have limited product lines, markets or financial resources, and may therefore be more vulnerable to adverse developments than larger capitalization companies.

TRADING HALT RISK—If a trading halt occurs, the Fund may temporarily be unable to purchase or sell certain securities, options or futures contracts. Such a trading halt near the time the Fund prices its shares may limit the Fund’s ability to use leverage and may prevent the Fund from achieving its investment objective.

U.S. GOVERNMENT SECURITIES RISK—U.S. government securities may or may not be backed by the full faith and credit of the U.S. government. U.S. government securities are subject to the risks associated with fixed-income and debt securities, particularly interest rate risk and credit risk.

Please retain this supplement for future reference.

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