Northwestern Mutual Series Fund, Inc.
Supplement Dated September 9, 2026, to the
Statutory Prospectus Dated May 1, 2026, as previously supplemented
The following information supplements the Statutory Prospectus for the Northwestern Mutual Series Fund, Inc. (the “Fund”) dated May 1, 2026 (the “Prospectus”). You should read this Supplement together with the Prospectus.
Portfolio Managers Update – Large Cap Blend Portfolio
Shilpee Raina no longer serves as a portfolio manager
for the Large Cap Blend Portfolio (the “Portfolio”), and David Maccarrone has joined Scott B. Davis as a portfolio manager, effective September 1, 2026.
Accordingly, the “Portfolio Manager” information set forth under the “Summary – PORTFOLIO MANAGEMENT” section is hereby deleted and replaced with the following:
“Portfolio Managers: Scott B. Davis, Managing Director, joined JP Morgan in 2006 and has
managed the Portfolio since 2023.
David Maccarrone, Managing
Director, joined JP Morgan in 2010 and has managed the Portfolio since 2026.”
In addition, the following text replaces the
information that appears in the Prospectus under the heading “THE INVESTMENT ADVISER AND SUB-ADVISERS – Portfolio Managers – Large Cap Blend Portfolio”:
“Scott B. Davis, Managing Director, joined J.P. Morgan Investment Management Inc. in 2006,
previously worked as an analyst in the U.S. Equity Research Group, became a portfolio manager in 2013 and has managed the Portfolio since 2023.
David Maccarrone, CFA
charterholder, Managing Director, joined J.P. Morgan Investment Management Inc. in 2010, previously worked as an Equity Research Analyst analyzing
and investing in North American and European commodities stocks, and has managed the Portfolio since 2026.”
Please retain this Supplement for future reference.