SPDR^® Series Trust

Supplement dated July 7, 2021 to the currently effective Statements of Additional Information (“SAIs”),

each as may be supplemented from time to time

Effective immediately, the section of the SAIs entitled “DETERMINATION OF NET ASSET VALUE”

is deleted in its entirety and replaced with the following:

DETERMINATION OF NET ASSET VALUE

The following information supplements and should be read in conjunction with the sections in the Prospectus entitled “PURCHASE AND SALE INFORMATION” and “ADDITIONAL PURCHASE AND SALE INFORMATION.”

NAV per Share for each Fund is computed by dividing the value of the net assets of the Fund (i.e., the value of its total assets less total liabilities) by the total number of Shares outstanding. Expenses and fees, including the management fees, are accrued daily and taken into account for purposes of determining NAV. The NAV of each Fund is calculated by State Street and determined once daily as of the close of the regular trading session on the NYSE (ordinarily 4:00 p.m. Eastern time) on each day that such exchange is open. Creation/redemption order cut-off times may be earlier on any day that the Securities Industry and Financial Markets Association (or applicable exchange or market on which a Fund’s investments are traded) announces an early closing time. Any assets or liabilities denominated in currencies other than the U.S. dollar are converted into U.S. dollars at market rates on the date of valuation (generally as of 4:00 p.m. London time) as quoted by one or more sources.

In calculating a Fund’s NAV per Share, the Fund’s investments are generally valued using market valuations. A market valuation generally means a valuation (i) obtained from an exchange, a pricing service, or a major market maker (or dealer), (ii) based on a price quotation or other equivalent indication of value supplied by an exchange, a pricing service, or a major market maker (or dealer) or (iii) based on amortized cost. A Fund relies on a third-party service provider for assistance with the daily calculation of the Fund’s NAV. The third-party service provider, in turn, relies on other parties for certain pricing data and other inputs used in the calculation of the Fund’s NAV. Therefore, a Fund is subject to certain operational risks associated with reliance on its service provider and that service provider’s sources of pricing and other data. NAV calculation may be adversely affected by operational risks arising from factors such as errors or failures in systems and technology. Such errors or failures may result in an inaccurately calculated NAV, delays in the calculation of a NAV and/or the inability to calculate a NAV over extended time periods. A Fund may be unable to recover any losses associated with such failures. In the case of shares of other funds that are not traded on an exchange, a market valuation means such fund’s published NAV per share. A price obtained from a pricing service based on such pricing service’s valuation matrix may be considered a market valuation. The Adviser may use various pricing services, or discontinue the use of any pricing service, as approved by the Board from time to time. Fixed-income assets are generally valued as of the announced closing time for trading in fixed-income instruments in a particular market or exchange, and generally 4:00 p.m. EST for U.S. fixed-income assets. Fixed-income assets are generally valued at the mean of the bid and ask prices for bank loans and inflation protected securities, and at the bid price for all other fixed-income assets.

In the event that current market valuations are not readily available or are deemed unreliable, the Trust’s procedures require the Oversight Committee to determine a security’s fair value if a market price is not readily available. In determining such value the Oversight Committee may consider, among other things, (i) price comparisons among multiple sources, (ii) a review of corporate actions and news events, and (iii) a review of relevant financial indicators (e.g., movement in interest rates, market indices, and prices from each Fund’s Index Provider). In these cases, the Fund’s NAV may reflect certain portfolio securities’ fair values rather than their market prices. The fair value of a portfolio instrument is generally the price which a Fund might reasonably expect to receive upon its current sale in an orderly market between market participants. Ascertaining fair value requires a determination of the amount that an arm’s-length buyer, under the circumstances, would currently pay for the portfolio instrument. Fair value pricing involves subjective judgments and it is possible that the fair value determination for a security is materially different than the value that could be realized upon the sale of the security. In addition, fair value pricing could result in a difference between the prices used to calculate a Fund’s NAV and the prices used by the Fund’s benchmark Index. This may result in a difference between the Fund’s performance and the performance of the applicable Fund’s benchmark Index. With respect to securities that are primarily listed on foreign exchanges, the value of a Fund’s portfolio securities may change on days when you will not be able to purchase or sell your Shares.

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

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SPDR^® Series Trust

Supplement dated July 7, 2021 to the Statement of Additional Information (“SAI”),

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

Effective immediately, the section of the SAI entitled “DETERMINATION OF NET ASSET VALUE”

is deleted in its entirety and replaced with the following:

DETERMINATION OF NET ASSET VALUE

The following information supplements and should be read in conjunction with the sections in the applicable Prospectus entitled “PURCHASE AND SALE INFORMATION” and “ADDITIONAL PURCHASE AND SALE INFORMATION.”

NAV per Share for each Fund is computed by dividing the value of the net assets of the Fund (i.e., the value of its total assets less total liabilities) by the total number of Shares outstanding. Expenses and fees, including the management fees, are accrued daily and taken into account for purposes of determining NAV. The NAV of each Fund other than the SPDR Bloomberg Barclays 1-3 Month T-Bill ETF is calculated by State Street and determined once daily as of the close of the regular trading session on the NYSE (ordinarily 4:00 p.m. Eastern time) on each day that such exchange is open. With respect to the SPDR Bloomberg Barclays 1-3 Month T-Bill ETF, the Fund’s NAV is calculated and determined twice daily on each day the NYSE is open at the following times: (i) 12:00 p.m. Eastern time; and (ii) at the close of the regular trading session on the NYSE. Creation/redemption order cut-off times may be earlier on any day that the Securities Industry and Financial Markets Association (or applicable exchange or market on which a Fund’s investments are traded) announces an early closing time. Any assets or liabilities denominated in currencies other than the U.S. dollar are converted into U.S. dollars at market rates on the date of valuation (generally as of 4:00 p.m. London time) as quoted by one or more sources.

In calculating a Fund’s NAV per Share, the Fund’s investments are generally valued using market valuations. A market valuation generally means a valuation (i) obtained from an exchange, a pricing service, or a major market maker (or dealer), (ii) based on a price quotation or other equivalent indication of value supplied by an exchange, a pricing service, or a major market maker (or dealer) or (iii) based on amortized cost. A Fund relies on a third-party service provider for assistance with the daily calculation of the Fund’s NAV. The third-party service provider, in turn, relies on other parties for certain pricing data and other inputs used in the calculation of the Fund’s NAV. Therefore, a Fund is subject to certain operational risks associated with reliance on its service provider and that service provider’s sources of pricing and other data. NAV calculation may be adversely affected by operational risks arising from factors such as errors or failures in systems and technology. Such errors or failures may result in an inaccurately calculated NAV, delays in the calculation of a NAV and/or the inability to calculate a NAV over extended time periods. A Fund may be unable to recover any losses associated with such failures. In the case of shares of other funds that are not traded on an exchange, a market valuation means such fund’s published NAV per share. A price obtained from a pricing service based on such pricing service’s valuation matrix may be considered a market valuation. The Adviser may use various pricing services, or discontinue the use of any pricing service, as approved by the Board from time to time. Fixed-income assets are generally valued as of the announced closing time for trading in fixed-income instruments in a particular market or exchange, and generally 4:00 p.m. EST for U.S. fixed-income assets (except U.S. fixed-income assets are generally valued as of 12:00 p.m. EST for the SPDR Bloomberg Barclays 1-3 Month T-Bill ETF’s 12:00 p.m. Eastern time NAV calculation). Fixed-income assets are generally valued at the mean of the bid and ask prices for bank loans and inflation protected securities, and at the bid price for all other fixed-income assets.

In the event that current market valuations are not readily available or are deemed unreliable, the Trust’s procedures require the Oversight Committee to determine a security’s fair value if a market price is not readily available. In determining such value the Oversight Committee may consider, among other things, (i) price comparisons among multiple sources, (ii) a review of corporate actions and news events, and (iii) a review of relevant financial indicators (e.g., movement in interest rates, market indices, and prices from each Fund’s Index Provider). In these cases, the Fund’s NAV may reflect certain portfolio securities’ fair values rather than their market prices. The fair value of a portfolio instrument is generally the price which a Fund might reasonably expect to receive upon its current sale in an orderly market between market participants. Ascertaining fair value requires a determination of the amount that an arm’s-length buyer, under the circumstances, would currently pay for the portfolio instrument. Fair value pricing involves subjective judgments and it is possible that the fair value determination for a security is materially different than the value that could be realized upon the sale of the security. In addition, fair value pricing could result in a difference between the prices used to calculate a Fund’s NAV and the prices used by the Fund’s benchmark Index. This may result in a difference between the Fund’s performance and the performance of the applicable Fund’s benchmark Index. With respect to securities that are primarily listed on foreign exchanges, the value of a Fund’s portfolio securities may change on days when you will not be able to purchase or sell your Shares.

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

070721SUPP3