Before you invest, you may want to
review the Portfolio’s prospectus, which contains more information about the Portfolio and its risks. You can find the
Portfolio’s prospectus, reports to shareholders, and other information about the Portfolio online at www.nmseriesfund.com.
You can also get this information at no cost by calling (866) 910-1232 or by sending an e-mail request to
sfprospectus@northwesternmutual.com. The current prospectus and statement of additional information, each dated May 1, 2026,
along with the Portfolio’s most recent annual report dated December 31, 2025, are incorporated by reference into this
Summary Prospectus. The Portfolio’s statement of additional information and annual report may be obtained, free of charge, in the same manner
as the prospectus.
The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.
The investment objective of the Portfolio is to seek capital appreciation.
FEES AND EXPENSES OF THE PORTFOLIO
The table below describes the fees and expenses that you may pay when you buy, hold, and sell interests in a separate account that invests in shares of the Portfolio as a result of your purchase of a variable annuity contract or variable life insurance policy. The fees and expenses shown in the table and Example do not reflect fees and expenses separately charged by variable annuity contracts or variable life insurance policies. If the fees and expenses separately charged by variable annuity contracts and variable life insurance policies were included, the fees and expenses shown in the table and the Example would be higher.
Example
This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other
mutual funds. The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and then redeem or hold
all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same.
The Example reflects adjustments made to the Portfolio’s operating expenses due to the fee waiver agreement with the
investment adviser for the first year only. Although your actual costs may be higher or lower, based on these assumptions your costs would
be:
Portfolio Turnover
The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 42% of
the average value of its portfolio.
PRINCIPAL
INVESTMENT STRATEGIES
The Portfolio normally invests primarily in
foreign equity securities, including emerging market equity securities. The Portfolio normally invests its assets across different industries, sectors,
countries, and regions, but the Portfolio may invest a significant percentage of its assets in issuers in a single industry, sector, country, or a particular
geographic region.
In conjunction with a team
of investment research analysts, sector leaders select investments for the Portfolio. The adviser generally manages the Portfolio to align with the MSCI
EAFE® (Europe-Australasia-Far East) Index (the
“Index”) with respect to sector weightings. The Portfolio does not, as a matter of policy, concentrate in any particular industry. The
Portfolio is not constrained by any particular investment style. The adviser may invest the Portfolio’s assets in the stocks of companies it
believes to have above average earnings growth potential compared to other companies (growth companies), in the stocks of companies it believes are
undervalued compared to their perceived worth (value companies), or in a combination of growth and value companies. The