0000719451 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:InterestRateChangesMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:PrepaymentMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IssuerSpecificChangesMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:USGovernmentObligationsRiskMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member oef:RiskNotInsuredDepositoryInstitutionMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member oef:RiskLoseMoneyMember 2026-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2016-01-01 2016-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2017-01-01 2017-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2018-01-01 2018-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2019-01-01 2019-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2020-01-01 2020-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2021-01-01 2021-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2022-01-01 2022-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2023-01-01 2023-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2024-01-01 2024-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2025-01-01 2025-12-31 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2025-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2021-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member 2016-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsMember 2025-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsMember 2021-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsMember 2016-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsAndSalesMember 2025-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsAndSalesMember 2021-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:C000014122Member oef:AfterTaxesOnDistributionsAndSalesMember 2016-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB069Member 2025-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB069Member 2021-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB069Member 2016-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB001Member 2025-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB001Member 2021-01-29 2026-01-29 0000719451 fmr:FidelityLimitedTermGovernmentFund-PROMember fmr:S000005156Member fmr:IndexLB001Member 2016-01-29 2026-01-29 iso4217:USD pure 485BPOS 2026-01-29 false 0000719451 N-1A Fidelity Advisor Series IV Fund Summary Fund: Fidelity® Limited Term Government Fund Investment Objective Fidelity® Limited Term Government Fund seeks a high level of current income in a manner consistent with preserving principal. Fee Table The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions, which are not reflected in the tables and examples below. Shareholder fees 0 Annual Operating Expenses 0.0020 0 0.0010 0.0030 This example helps compare the cost of investing in the fund with the cost of investing in other funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund 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 shares at the end of each time period indicated: 31 97 169 381 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 48 % of the average value of its portfolio. 0.48 Principal Investment Strategies Normally investing at least 80% of assets in U.S. Government securities and repurchase agreements for those securities. U.S. Government securities are high-quality securities issued or guaranteed by the U.S. Treasury or by an agency or instrumentality of the U.S. Government. U.S. Government securities may be backed by the full faith and credit of the U.S. Treasury, the right to borrow from the U.S. Treasury, or the agency or instrumentality issuing or guaranteeing the security. Certain issuers of U.S. Government securities, including Fannie Mae, Freddie Mac, and the Federal Home Loan Banks, are sponsored or chartered by Congress but their securities are neither issued nor guaranteed by the U.S. Treasury. 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. 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. 1-5 Year Government Bond Index. Normally maintaining a dollar-weighted average maturity between two and five years. Allocating assets across different market sectors and maturities. Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments. Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. 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. U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. 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 information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares 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. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares 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 Year-by-Year Returns 0.0058 0.0057 0.0115 0.0375 0.0391 -0.0146 -0.0618 0.0411 0.0310 0.0564    Highest Quarter Return 0.0369 2020-03-31    Lowest Quarter Return -0.0348 2022-03-31 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 0.0564 0.0095 0.0146 Return After Taxes on Distributions 0.0422 0.0015 0.0078 Return After Taxes on Distributions and Sale of Fund Shares 0.0332 0.0038 0.0083 Bloomberg U.S. 1-5 Year Government Bond Index 0.0583 0.0129 0.0182 Bloomberg U.S. Aggregate Bond Index 0.0730 -0.0036 0.0201