Strategy. Investing primarily in a combination of Fidelity U.S. equity funds, international equity funds, bond funds, and short-term funds (underlying Fidelity funds), each of which (excluding any money market fund) seeks to provide investment results that correspond to the total return of a specific index. Allocating assets according to an asset allocation strategy shown in the glide path below that adjusts over time until it reaches an allocation similar to that of the Fidelity Freedom Index Income Fund, approximately 10 to 19 years after the year 2005. Fidelity Management & Research Company LLC (FMR) (the Adviser) may modify the fund's asset allocations from time to time when in the interests of shareholders. The asset allocation shown in the glide path depicts … Show more… Investing primarily in a combination of Fidelity U.S. equity funds, international equity funds, bond funds, and short-term funds (underlying Fidelity funds), each of which (excluding any money market fund) seeks to provide investment results that correspond to the total return of a specific index. Allocating assets according to an asset allocation strategy shown in the glide path below that adjusts over time until it reaches an allocation similar to that of the Fidelity Freedom Index Income Fund, approximately 10 to 19 years after the year 2005. Fidelity Management & Research Company LLC (FMR) (the Adviser) may modify the fund's asset allocations from time to time when in the interests of shareholders. The asset allocation shown in the glide path depicts the allocation to U.S. equity funds, international equity funds, bond funds (including U.S. investment grade bond, international bond, inflation-protected bond, and long-term treasury bond), and short-term funds. Buying and selling futures contracts (both long and short positions) in an effort to manage cash flows efficiently, remain fully invested, or facilitate asset allocation. The Adviser, under normal market conditions, will make investments that are consistent with seeking high total return for several years beyond the fund's target retirement date in an effort to achieve the fund's overall investment objective. Using an asset allocation among underlying Fidelity funds and futures as of April 1, 2024, of approximately: U.S. Equity Funds 11% International Equity Funds 8% International Bond Funds 5% U.S. Investment Grade Bond Funds 43% Long-Term Treasury Bond Funds 3% Long-Term Inflation-Protected Bond Funds 0% Short-Term Inflation-Protected Bond Funds 20% Short-Term Funds 10% * The Adviser may change these percentages over time. The allocation percentages may not add to 100% due to rounding. Designed for investors who retired in or within a few years of 2005 (target retirement date) at or around age 65. When the asset allocation of a fund matches Fidelity Freedom Index Income Fund's asset allocation (approximately 10 to 19 yearsafter the year indicated in the fund's name), the Board of Trusteesmay combine the fund with Fidelity Freedom Index Income Fund,without shareholder approval, and the fund's shareholders willbecome shareholders of Fidelity Freedom Index Income Fund. Reorganization. Fidelity Freedom Index 2005 Fund (the "Fund") has changed its asset allocation over time following its predetermined glide path and its allocations now match those of the Fidelity Freedom Index Income Fund (the "Income Fund"). As described in the Funds' prospectus, once the Funds' asset allocations match, the Board of Trustees of Fidelity Aberdeen Street Trust (the "Trust") may approve combining the Fund with the Income Fund if the Board determines that the combination is in the best interest of the Fund and its shareholders. At its January 2024 meeting, the Board of Trustees of the Trust unanimously approved an Agreement and Plan of Reorganization ("Agreement") between the Fund and the Income Fund. The Income Fund seeks high current income and, as a secondary objective, capital appreciation. The Fund seeks high total return until its target retirement date. Thereafter the Fund's objective will be to seek high current income and, as a secondary objective, capital appreciation. The Agreement provides for the transfer of all of the assets and the assumption of all of the liabilities of the Fund in exchange for shares of the Income Fund equal in total value to the total value of shares of the Fund. After the exchange, the Fund will distribute the Income Fund shares to its shareholders pro rata, in liquidation of the Fund (these transactions are referred to as the "Reorganization"). The Reorganization, which does not require shareholder approval, is expected to take place on or about June 14, 2024 (the "Closing Date"). The Reorganization is expected to be a tax-free transaction. This means that neither the Fund nor its shareholders will recognize any gain or loss as a direct result of the Reorganization. Shareholders of the Fund should carefully consider whether the Income Fund's principal investment strategies, limitations and risks (as set forth in the Income Fund's prospectus) will meet their investment needs. Fund shareholders who do not wish to own Income Fund shares may: (1) redeem Fund shares or (2) exchange Fund shares for shares of another Fidelity fund for which they are eligible prior to the Closing Date. Please note that if shares are held in a taxable account, a redemption or exchange will be a taxable event and may result in gain or loss in connection with the transaction. For more detailed information, please contact Fidelity at 1-800-835-5092 (plan accounts) or 1-800-544-8544 (all other accounts). Show less