497K 1 filing8801.htm PRIMARY DOCUMENT
Supplement to the
Fidelity Flex® Funds
Fidelity Flex® Mid Cap Index Fund
June 29, 2024
Summary Prospectus
 
The following information replaces similar information found in the "Fund Summary" section under the "Investment Objective" heading.
Fidelity Flex® Mid Cap Index Fund seeks to provide investment results that correspond to the total return of stocks of mid-capitalization U.S. companies.
The following information replaces similar information found in the "Fund Summary" section under the "Principal Investment Strategies" heading.
  • Prior to August 21, 2025, normally investing at least 80% of assets in securities included in the Russell Midcap® Index. The Russell Midcap® Index is a market capitalization-weighted index of medium-capitalization U.S. company stocks.
  • Effective August 21, 2025, normally investing at least 80% of assets in securities included in the Fidelity U.S. Mid Cap IndexSM.
The Fidelity U.S. Mid Cap IndexSM is a float-adjusted market capitalization-weighted index designed to reflect the performance of stocks of U.S. mid-capitalization companies. It is a subset of the Fidelity U.S. Total Investable Market IndexSM (a float-adjusted market capitalization-weighted index designed to reflect the performance for the U.S. equity market, including large-, mid-, and small-capitalization stocks). Mid-capitalization stocks are considered to be stocks whose market capitalization is similar to the market capitalization of companies in the Russell Midcap® Index or the S&P MidCap 400® Index.
The Fidelity U.S. Mid Cap IndexSM was created by Fidelity Product Services LLC (FPS) using a rules-based proprietary index methodology that includes all U.S. stocks meeting certain market capitalization, liquidity, and investability requirements.
  • Lending securities to earn income for the fund.
The following information supplements information found in the "Fund Summary" section under the "Principal Investment Risks" heading.
  • Rules-Based Strategy Risk.
Although the index uses a rules-based proprietary index methodology, there is no guarantee that this methodology will be successful. 
ZMP-SUSTK-0425-100
1.9919857.100
April 1, 2025