Important Notice Regarding Change in

Investment Objective and Related Matters

SSGA Active Trust

SPDR SSGA Ultra Short Term Bond ETF

(the “Fund”)

Supplement dated May 21, 2021 to the Prospectus and Summary Prospectus,

each dated October 31, 2020, as may be supplemented from time to time

Effective June 21, 2021 (the “Effective Date”), the Fund’s investment objective and principal strategy will change. Accordingly, as of the Effective Date:

1) The section entitled “INVESTMENT OBJECTIVE” page 1 of the Prospectus and Summary Prospectus is replaced in its entirety with the following:

The SPDR SSGA Ultra Short Term Bond ETF (the “Fund”) seeks to maximize current income consistent with preservation of capital and daily liquidity.

2) “THE FUND’S PRINCIPAL INVESTMENT STRATEGY” section beginning on page 62 of the Prospectus and page 2 of the Summary Prospectus is replaced in its entirety with the following:

SSGA Funds Management, Inc. (the “Adviser” or “SSGA FM”) invests, under normal circumstances, at least 80% of the Fund’s net assets (plus the amount of borrowings for investment purposes) in a diversified portfolio of U.S. dollar-denominated investment-grade fixed income securities. Investment-grade fixed income securities are instruments that are rated at the time of purchase BBB- or higher by Standard & Poor’s Financial Services LLC and/or Fitch Inc., or Baa3 or higher by Moody’s Investors Service, Inc., or, if unrated, determined by the management team to be of equivalent quality. The Fund invests in fixed and floating rate securities of varying maturities, such as corporate obligations (including bonds, commercial paper of U.S. and foreign entities, master notes, and medium term notes); government bonds (including U.S. Treasury Bills, notes, and bonds); agency securities; privately-issued securities; asset-backed and mortgage-backed securities; money market instruments (including U.S. and foreign bank time deposits, certificates of deposit, and banker acceptances) and other investment companies. The Fund may invest up to 10% of the Fund’s net assets in high yield securities (commonly known as “junk bonds”). The Fund may also invest in exchange traded products (“ETPs”). ETPs include exchange traded funds registered under the Investment Company Act of 1940, as amended (the “1940 Act”) (“Underlying ETFs”) and exchange traded notes (“ETNs”). In addition, the Fund may invest in certain ETPs that pay fees to the Adviser and its affiliates for management, marketing or other services.

Under normal circumstances, the effective duration of the Fund is expected to be one year or less. Effective duration is a measure of the Fund’s price sensitivity to changes in yields or interest rates; however, investors should be aware that effective duration is not an exact measurement and may not reliably predict a particular security’s price sensitivity to changes in yield or interest rates. In addition, under normal circumstances the Fund expects to maintain a weighted average maturity that is two and a half years or less. Weighted average maturity is a U.S. dollar-weighted average of the remaining term to maturity of the underlying securities in the Fund. For the purposes of determining the Fund’s weighted average maturity, a security’s final maturity date, or for amortizing securities such as asset-backed and mortgage-backed securities, its weighted average life will be used for calculation purposes. The Adviser buys and sells securities for the Fund based on its analysis of credit quality and overall portfolio duration. The Adviser may also use derivative instruments (primarily futures contracts, interest rate and credit default swaps, and options on treasury futures) to manage yield, interest rate exposure (also known as duration), weighted average maturity, and exposure to credit quality. As of

July 31, 2020, a significant portion of the Fund comprised securities of companies in the financial and industrial sectors, although this may change from time to time. The Fund is not a money market fund and does not seek to maintain a stable net asset value of $1.00 per share.

3) The “PRINCIPAL RISKS OF INVESTING IN THE FUND” section beginning on page 63 of the Prospectus and page 2 of the Summary Prospectus is updated to add the following risks as principal risks of the Fund.

Below Investment-Grade Securities Risk: Lower-quality debt securities (“high yield” or “junk” bonds) are considered predominantly speculative, and can involve a substantially greater risk of default than higher quality debt securities. Issuers of lower-quality debt securities may have substantially greater risk of insolvency or bankruptcy than issuers of higher-quality debt securities. They can be illiquid, and their values can have significant volatility and may decline significantly over short periods of time. Lower-quality debt securities tend to be more sensitive to adverse news about the issuer, or the market or economy in general.

Counterparty Risk: The Fund will be subject to credit risk with respect to the counterparties with which the Fund enters into derivatives contracts, repurchase agreements, reverse repurchase agreements, and other transactions. If a counterparty fails to meet its contractual obligations, the Fund may be unable to terminate or realize any gain on the investment or transaction, or to recover collateral posted to the counterparty, resulting in a loss to the Fund. If the Fund holds collateral posted by its counterparty, it may be delayed or prevented from realizing on the collateral in the event of a bankruptcy or insolvency proceeding relating to the counterparty.

Derivatives Risk: Derivative transactions can create investment leverage and may have significant volatility. It is possible that a derivative transaction will result in a much greater loss than the principal amount invested, and the Fund may not be able to close out a derivative transaction at a favorable time or price. The counterparty to a derivatives contract may be unable or unwilling to make timely settlement payments, return the Fund’s margin, or otherwise honor its obligations. A derivatives transaction may not behave in the manner anticipated by the Adviser or may not have the effect on the Fund anticipated by the Adviser.

4) The risk chart within the “ADDITIONAL RISK INFORMATION” section of the Prospectus is updated to reflect that “Below Investment-Grade Securities Risk”, “Counterparty Risk”, “Derivatives Risk”, and “Liquidity Risk” are principal risks of the Fund. In addition, “Futures Contract Risk; Other Exchange-Traded Derivatives Risk”, “Options Risk” and “Swaps Risk” are added to the risk chart as principal risks of the Fund and the following risk discussions are added beneath the risk chart:

Futures Contract Risk; Other Exchange-Traded Derivatives Risk. The risk of loss relating to the use of futures contracts and other exchange-traded derivatives is potentially unlimited. The ability to establish and close out positions in futures contracts and other exchange-traded derivatives will be subject to the development and maintenance of a liquid secondary market. There is no assurance that a liquid secondary market on an exchange will exist for any particular futures contract or other exchange-traded derivative or at any particular time. In the event no such market exists for a particular derivative, it might not be possible to effect closing transactions, and the Fund will be unable to terminate the derivative. In using futures contracts and other exchange-traded derivatives, the Fund will be reliant on the ability of the Adviser to predict market and price movements correctly; the skills needed to use such derivatives successfully are different from those needed for traditional portfolio management. If the Fund uses futures contracts or other exchange-traded derivatives for hedging purposes, there is a risk of imperfect correlation between movements in the prices of the derivatives and movements in the securities or index underlying the derivatives or movements in the prices of the Fund’s investments that are the subject of such hedge. The prices of futures and other exchange-traded derivatives, for a number of reasons, may not correlate perfectly with movements in the securities or index underlying them. For example, participants in the futures markets and in markets for other exchange-traded derivatives are subject to margin deposit requirements. Such requirements may cause investors to take

actions with respect to their derivatives positions that they would not otherwise take. The margin requirements in the derivatives markets may be less onerous than margin requirements in the securities markets in general, and as a result those markets may attract more speculators than the securities markets do. Increased participation by speculators in those markets may cause temporary price distortions. Due to the possibility of price distortion, even a correct forecast of general market trends by the Adviser still may not result in a successful derivatives activity over a very short time period. The risk of a position in a futures contract or other exchange-traded derivative may be very large compared to the relatively low level of margin the Fund is required to deposit. In many cases, a relatively small price movement in a futures contract may result in immediate and substantial loss or gain to the investor relative to the size of a required margin deposit. The Fund will incur brokerage fees in connection with its exchange-traded derivatives transactions. The Fund will typically be required to post margin with its futures commission merchant in connection with its transactions in futures contracts and other exchange-traded derivatives. In the event of an insolvency of the futures commission merchant or a clearing house, the Fund may not be able to recover all (or any) of the margin it has posted with the futures commission merchant, or to realize the value of any increase in the price of its positions, or it may experience a significant delay in doing so. The Fund also may be delayed or prevented from recovering margin or other amounts deposited with a futures commission merchant or futures clearinghouse. The Commodity Futures Trading Commission (the “CFTC”) and the various exchanges have established limits referred to as “speculative position limits” on the maximum net long or net short positions that any person and certain affiliated entities may hold or control in a particular futures contract. Trading limits are imposed on the number of contracts that any person may trade on a particular trading day. An exchange may order the liquidation of positions found to be in violation of these limits and it may impose sanctions or restrictions. In addition, the Dodd-Frank Act requires the CFTC to establish speculative position limits on certain commodity futures contracts and their economically equivalent futures, options and swaps. Regulatory action taken by the CFTC to establish these additional position limits may adversely affect the market liquidity of the futures, options and economically equivalent derivatives in which the Fund may invest. It is possible that, as a result of such limits, the Fund’s Adviser will be precluded from taking positions in certain futures contracts or over-the-counter derivatives as a result of positions held by other clients of the Adviser or Sub-Adviser or by the Adviser or Sub-Adviser or its affiliates themselves.

Futures contracts and other exchange-traded derivatives traded on markets outside the U.S. are not generally subject to the same level of regulation by the CFTC or other U.S. regulatory entities as contracts traded in the U.S., including without limitation as to the execution, delivery, and clearing of transactions. U.S. regulators neither regulate the activities of a foreign exchange, nor have the power to compel enforcement of the rules of the foreign exchange or the laws of the foreign country in question. Margin and other payments made by a Fund may not be afforded the same protections as are afforded those payments in the U.S., including in connection with the insolvency of an executing or clearing broker or a clearinghouse or exchange. Certain foreign futures contracts and other exchange-traded derivatives may be less liquid and more volatile than U.S. contracts.

Options Risk. The successful use of the Fund’s options strategies depends on the ability of the Adviser to forecast market movements correctly. For example, if the Fund were to write a call option on a security based on the Adviser’s expectation that the price of the security would fall, but the price were to rise instead, the Fund could be required to sell the security upon exercise at a price below the current market price. Similarly, if the Fund were to write a put option based on the Adviser’s expectation that the price of the underlying security would rise, but the price were to fall instead, the Fund could be required to purchase the security upon exercise at a price higher than the current market price. When the Fund purchases an option, it runs the risk that it will lose its entire investment in the option in a relatively short period of time, unless the Fund exercises the option or enters into a closing sale transaction before the option’s expiration. If the price of the underlying security does not rise (in the case of a call) or fall (in the case of a put) to an extent sufficient to cover the option premium and transaction costs, the Fund will lose part or all of its investment in the option. This contrasts with an investment by the Fund in the underlying security, since the Fund will not realize a loss if the security’s price does not change over a relatively short time period. The effective use of options also depends on

the Fund’s ability to terminate option positions at times when the Adviser deems it desirable to do so. There is no assurance that the Fund will be able to effect closing transactions at any particular time or at an acceptable price. The sale of options by the Fund may create investment leverage.

Swaps Risk. A swap is a two-party contract that generally obligates one party to pay the positive return and the other party to pay the negative return on a specified reference security, basket of securities, security index or index component. Swaps can involve greater risks than direct investment in securities, because swaps may be leveraged and are subject to counterparty risk (e.g., the risk of a counterparty’s defaulting on the obligation or bankruptcy), credit risk and pricing risk (i.e., swaps may be difficult to value). Swaps may also be considered illiquid. It may not be possible for a Fund to liquidate a swap position at an advantageous time or price, which may result in significant losses.

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

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