Mason Street Advisors, LLC (MSA) is the principal investment adviser for all the Portfolios in the Northwestern Mutual Series Fund (Series Fund). (Portfolios in the Series Fund are identified by the parenthetical next to the portfolio name.) MSA has engaged and oversees sub-advisers who provide day-to-day management for certain of the Series Fund Portfolios. Each sub-adviser may be replaced without the approval of shareholders. Please see the prospectus for more information. Additional fund options are advised by Russell Investments, Fidelity Investments, Neuberger Berman Investment Advisers LLC and Credit Suisse Asset Management, LLC.