B-1 STATEMENT OF ADDITIONAL INFORMATION Dated May 1 ...

Name of Portfolio 2008 2007 2006Small Cap Growth Stock Portfolio 2,282,863 2,933,027 2,852,064Small Cap Value Portfolio 2,621,643 2,986,778 2,411,883International Growth Portfolio 1,854,248 2,123,588 1,549,674International Equity Portfolio 8,780,948 10,407,309 8,663,137Money Market Portfolio 1,620,124 1,265,590 1,105,835Select Bond Portfolio 3,402,348 3,048,972 2,527,449High Yield Bond Portfolio 1,202,993 1,316,710 1,175,924Balanced Portfolio 7,505,071 8,833,417 8,655,900Asset Allocation Portfolio 1,235,330 1,420,350 1,398,805With respect to certain Portfolios, Mason Street Advisors has contractually agreed to waive itsadvisory fees and to absorb certain other operating expenses to the extent necessary so that total operatingexpenses for such Portfolios do not exceed the amounts reflected in the following table. Each suchagreement is in effect until April 30, 2010, and may be terminated at any time thereafter.PortfolioFocused Appreciation 0.90%Domestic Equity 0.75%Equity Income 0.75%Mid Cap Value 1.00%Small Cap Value 1.00%International Growth 1.10%Asset Allocation 0.75%In addition, Mason Street Advisers has agreed to waive its management fee with respect to (1) theInternational Equity Portfolio effective November 16, 2006, such that the management fee is 0.80% onthe first $50 million of assets, 0.60% on assets from $50 million to $1 billion, 0.58% on assets from $1billion to $1.5 billion and 0.51% on assets in excess of $1.5 billion (the latter waiver was added effectiveDecember 12, 2006), and (2) the Asset Allocation Portfolio, such that the management fee is 0.55% onthe first $100 million of assets, 0.45% on assets from $100 million to $250 million, and 0.35% on assetsin excess of $250 million, each until April 30, 2010.Mason Street Advisors employs a staff of investment professionals to manage the assets of the Fundand the other advisory clients of Mason Street Advisors. Northwestern Mutual provides related facilitiesand personnel which are utilized by Mason Street Advisors in performing its obligations under theAgreements.“Northwestern Mutual Life” is the name and service mark of The Northwestern Mutual LifeInsurance Company and the right of the Fund to use the name and mark is subject to the consent ofNorthwestern Mutual. Under the Agreement providing such consent, the Fund recognizes the prior rightsof Northwestern Mutual in the name and mark, agrees that use of the name and mark by the Fund willinure to the benefit of Northwestern Mutual and agrees that its right to use the name and mark can beterminated by Northwestern Mutual and will automatically be terminated if at any time Mason StreetAdvisors ceases to be the investment adviser to the Fund or if Mason Street Advisors ceases to be anaffiliated company of Northwestern Mutual.The Sub-AdvisersAmerican Century Investment Management, Inc. (“American Century”), 4500 Main Street, KansasCity, Missouri 64111, provides investment services to the Mid Cap Value Portfolio, pursuant to aninvestment sub-advisory agreement. American Century has been managing funds since 1958. It isresponsible for managing the investments of the Mid Cap Value Portfolio and directing the purchase andsale of their investment securities. For the services provided for the Mid Cap Value Portfolio, MasonStreet Advisors pays American Century a fee at an annual rate of 0.57% on the first $50 million, 0.52%B-51