Supplement to the

Fidelity® SAI Municipal Bond Index Fund

August 29, 2024

Summary Prospectus

Michael Maka no longer serves as Co-Portfolio Manager of the fund.

The following information supplements information found in the "Fund Summary" section under the "Portfolio Manager(s)" heading.

Mark Lande (Co-Portfolio Manager) has managed the fund since 2024.

MBX-SUSTK-1024-101 1.9900310.101 October 1, 2024