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485BPOS 2026-06-12 false 0000035315 N-1A Fidelity Salem Street Trust Fund Summary Fund /Class: Fidelity® Short-Term Bond Fund /ETF Class   Investment Objective Fidelity® Short-Term Bond Fund seeks to obtain a high level of current income consistent with preservation of capital. Fee Table The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund's ETF Class. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. Shareholder fees 0 Annual Operating Expenses 0.0020 0 0.0001 0.0021 -0.0001 0.0020 Based on estimated amounts for the current fiscal year. 2027-12-31 This example helps compare the cost of investing in the fund's ETF Class with the cost of investing in other funds or classes. Let's say, hypothetically, that the annual return for ETF Class shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund's ETF Class are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your ETF Class shares at the end of each time period indicated: 20 66 117 266 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 operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 59 % of the average value of its portfolio. 0.59 Principal Investment Strategies Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities. Debt securities are used by issuers to borrow money. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security. Debt securities include corporate bonds, government securities (including Treasury securities), repurchase agreements, money market securities, mortgage and other asset-backed securities, loans and loan participations, and other securities, such as hybrids and synthetic securities, believed to have debt-like characteristics (e.g., securities classified as Tier 2 Regulatory capital, securities that rank above share capital in an insolvency waterfall, securities with maturity dates and non-cancellable interest payment structures).  Investment grade securities in which the fund invests include securities or issuers rated at least BBB- or its equivalent by at least one nationally recognized statistical ratings organization (NRSRO), or, if unrated, determined by the Adviser to be of comparable quality. A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price. Derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives. Managing the fund to have similar overall interest rate risk to the Bloomberg U.S. 1-3 Year Government/Credit Bond Index. Normally maintaining a dollar-weighted average maturity of three years or less. Allocating assets across different market sectors and maturities. Investing in domestic and foreign issuers. Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments. Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure. Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity® funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above. Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease. Fluctuation of Net Asset Value and Share Price. The net asset value per share (NAV) of the fund's ETF Class will generally fluctuate with changes in the market value of the fund's holdings. The fund's ETF Class shares can be bought and sold in the secondary market at market prices. Disruptions to creations and redemptions, the existence of extreme market volatility or potential lack of an active trading market for the fund's ETF Class shares may result in the fund's ETF Class shares trading significantly above (at a premium) or below (at a discount) to NAV. Given the nature of the relevant markets for certain of the fund's securities, the fund's ETF Class shares may trade at a larger premium or discount to the NAV than shares of other ETFs. In addition, in stressed market conditions or periods of market disruption or volatility, the market for the fund's ETF Class shares may become less liquid in response to deteriorating liquidity in the markets for the fund's underlying portfolio holdings. Trading Issues. There can be no assurance that an active trading market will be maintained. Market makers and Authorized Participants are not obligated to make a market in the fund's ETF Class shares or to submit purchase and redemption orders for creation units. Decisions by market makers or Authorized Participants to reduce their role with respect to market making or creation and redemption activities during times of market stress, or a decline in the number of Authorized Participants due to decisions to exit the business, bankruptcy, or other factors, could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying value of the fund's portfolio securities and the market price of the fund's ETF Class shares. In addition, trading may be halted, for example, due to market conditions. Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. Cash Transactions Risk. The fund may effect some or all creations and redemptions of its ETF Class shares using cash rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in a fund that effects ETF share class redemptions entirely in-kind. An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency .   You could lose money by investing in the fund. Performance The following information is intended to help you understand the risks of investing in the fund. The ETF Class shares are a new class of shares for which performance information is not available, and therefore, for periods prior to the inception of the ETF Class shares, the bar chart and table show performance information for the Fidelity® Short-Term Bond Fund shares of the fund, a mutual fund class of shares of the fund not offered in this Prospectus. Returns of the ETF Class shares of the fund may vary from the returns of the Fidelity® Short-Term Bond Fund shares due to differences in expenses. The information illustrates the changes in the performance of Fidelity® Short-Term Bond Fund, a class of shares of the fund, from year to year and compares the performance of this class to the performance of a securities market index and an additional index over various periods of time. The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance. Visit www.fidelity.com for more recent performance information for Fidelity® Short-Term Bond Fund, a class of shares of the fund. Performance history will be available at www.fidelity.com for ETF Class after ETF Class has been in operation for one calendar year. The information illustrates the changes in the performance of Fidelity® Short-Term Bond Fund, a class of shares of the fund, from year to year and compares the performance of this class to the performance of a securities market index and an additional index over various periods of time. Past performance (before and after taxes) is not an indication of future performance. www.fidelity.com Performance history will be available at www.fidelity.com for ETF Class after ETF Class has been in operation for one calendar year. Year-by-Year Returns 0.0145 0.0115 0.0119 0.0420 0.0370 -0.0073 -0.0362 0.0534 0.0471 0.0547    Highest Quarter Return 0.0298 2020-06-30    Lowest Quarter Return -0.0250 2022-03-31    Year-to-Date Return 0.0026 2026-03-31 * The returns shown above are for Fidelity® Short-Term Bond Fund, a class of shares of the fund that is not offered through this prospectus. ETF Class would have substantially similar annual returns to Fidelity® Short-Term Bond Fund because the classes are invested in the same portfolio of securities. ETF Class's returns would differ from Fidelity® Short-Term Bond Fund's returns only to the extent that the classes do not have the same expenses. Average Annual Returns After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares. Return Before Taxes 0.0547 0.0216 0.0225 Return After Taxes on Distributions 0.0365 0.0105 0.0132 Return After Taxes on Distributions and Sale of Fund Shares 0.0321 0.0118 0.0133 Bloomberg U.S. 1-3 Year Government/Credit Bond Index 0.0535 0.0197 0.0209 Bloomberg U.S. Aggregate Bond Index 0.0730 -0.0036 0.0201 * The returns shown above are for Fidelity® Short-Term Bond Fund, a class of shares of the fund that is not offered through this prospectus. ETF Class would have substantially similar annual returns to Fidelity® Short-Term Bond Fund because the classes are invested in the same portfolio of securities. ETF Class's returns would differ from Fidelity® Short-Term Bond Fund's returns only to the extent that the classes do not have the same expenses. A Based on estimated amounts for the current fiscal year. B Fidelity Management & Research Company LLC (FMR) has contractually agreed to reimburse ETF Class shares of the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, proxy and shareholder meeting expenses, extraordinary expenses, and acquired fund fees and expenses (including fees and expenses associated with a wholly owned subsidiary), if any, as well as non-operating expenses such as brokerage commissions and fees and expenses associated with the fund's securities lending program, if applicable), as a percentage of its average net assets, exceed 0.20% (the Expense Cap). If at any time during the current fiscal year expenses for ETF Class shares of the fund fall below the Expense Cap, FMR reserves the right to recoup through the end of the fiscal year any expenses that were reimbursed during the current fiscal year up to, but not in excess of, the Expense Cap. This arrangement will remain in effect through December 31, 2027 . FMR may not terminate this arrangement before the expiration date without the approval of the Board of Trustees and may extend it in its discretion after that date.