Multi-Sector Bond Portfolio
NORTHWESTERN MUTUAL SERIES FUND INC
Expense ratio
Net assets1
$1.36B
Holdings1
1063
Category
Allocation
Return

Investment objective & strategy

As of May 2, 2025 · prospectus

Objective. The investment objective of the Portfolio is to seek maximum total return, consistent with prudent investment management.

Strategy. Normally, the Portfolio invests at least 80% of net assets (plus any borrowings for investment purposes) in debt securities. The debt securities may be represented by forwards or derivatives such as options, futures contracts or swap agreements, including the purchase or sale of credit default swaps, and interest rate swaps (to take a position on interest rates moving either up or down) that have economic characteristics that are similar to the debt securities included in the 80% policy. The average portfolio duration of the Portfolio normally varies from three to eight years, based on the advisers forecast for interest rates. Duration is a measure of the sensitivity of the price of the Portfolios fixed income securities to changes in interest … Normally, the Portfolio invests at least 80% of net assets (plus any borrowings for investment purposes) in debt securities. The debt securities may be represented by forwards or derivatives such as options, futures contracts or swap agreements, including the purchase or sale of credit default swaps, and interest rate swaps (to take a position on interest rates moving either up or down) that have economic characteristics that are similar to the debt securities included in the 80% policy. The average portfolio duration of the Portfolio normally varies from three to eight years, based on the advisers forecast for interest rates. Duration is a measure of the sensitivity of the price of the Portfolios fixed income securities to changes in interest rates; the longer the duration, the more sensitive the price will be to changes in interest rates. The Portfolio may invest all of its assets in high yield securities subject to a maximum of 10% of its total assets in securities rated below B by Moodys or equivalently rated by S&P or Fitch or, if unrated, determined by the Portfolios adviser to be of comparable quality. High yield securities, commonly referred to as junk bonds, are non-investment grade securities. A security is considered to be non-investment grade when it is rated below investment grade by at least two of the three credit ratings agencies (BB+ or lower by S&P; Ba1 or lower by Moodys; BB+ or lower by Fitch) or if unrated, determined by the Portfolios adviser to be of comparable quality. The Portfolio may invest, without limitation, in securities denominated in foreign currencies and U.S. dollar denominated securities of foreign issuers. In addition, the Portfolio may invest without limit in fixed income securities of issuers that are economically tied to emerging securities markets. The Portfolio may invest in illiquid securities. The Portfolio may also invest up to 10% of its net assets in preferred stocks. The Portfolio may invest all of its assets in derivative instruments, such as options, futures contracts or swap agreements including the purchase or sale of credit defaults swaps, and interest rate swaps (to take a position on interest rates moving either up or down), in municipal bonds, contingent convertible securities, or in mortgage- or asset-backed securities, subject to the Portfolios objective and policies. The Portfolio may utilize currency forwards and currency options to manage or hedge currency exposure. The Portfolio may invest in mortgage- or asset-backed securities which are non-investment grade. Mortgage-backed securities may include residential and commercial mortgage-backed securities issued by a Federal agency and private label residential and commercial mortgage-backed securities. The adviser may invest in derivatives at any time it deems appropriate, generally when relative value and liquidity conditions make these investments more attractive relative to cash bonds. The Portfolio may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short sales. A short sale involves the sale of a security that is borrowed from a broker or other institution, and which must be purchased in the market at a later date and returned to the lender. The Portfolio may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as buy backs or dollar rolls). The Portfolio may invest up to 10% of its net assets in fixed- and floating-rate loans, including senior loans, and such investments may be in the form of loan participations and assignments. Senior loans are considered speculative instruments. The total return sought by the Portfolio consists of income earned on the Portfolios investments, plus capital appreciation, if any, which generally arises from a decrease in interest rates or improving credit fundamentals for a particular sector or security. The Portfolio may engage in frequent and active trading of portfolio securities to achieve its investment objective, particularly during periods of volatile market movements. In selecting securities for a Portfolio, the adviser develops an outlook for interest rates, foreign currency exchange rates and the economy, analyzes credit and call risks, which involves both macro and fundamental analysis. The proportion of a Portfolios assets committed to investment in securities with particular characteristics (such as quality, sector, interest rate or maturity) varies based on the advisers outlook for the U.S. and foreign economies, the financial markets and other factors. The adviser attempts to identify areas of the bond market that are undervalued relative to the rest of the market. The adviser identifies these areas by grouping bonds into the following sectors: money markets, governments, corporates, mortgages, asset-backed and international. Sophisticated proprietary software then assists in evaluating sectors and pricing specific securities. Once investment opportunities are identified, the adviser will shift assets among sectors depending upon changes in relative valuations and credit spreads. The Portfolio may sell a position when, in the advisers opinion, it no longer represents a good value, when a superior risk/return opportunity exists in a substitute position, or when it no longer fits within the Portfolios macroeconomic or structural strategy.

Top holdings

As of March 31, 2026 · N-PORT
SecurityTickerValue% of fund
FNCL 6.5 6/24 $80.30M 5.90%
DEUTSCHE TRIPARTY MTGE $72.90M 5.36%
Uniform Mortgage-Backed Security, TBA FNMA $29.02M 2.13%
FNCL 5 4/26 $20.41M 1.50%
Uniform Mortgage-Backed Security, TBA FNCL $19.65M 1.45%
Uniform Mortgage-Backed Security, TBA FNMA $19.01M 1.40%
US TREASURY N/B $17.92M 1.32%
Cashmere Valley Bank $17.39M 1.28%
EUROPEAN UNION MTN 3.000000% 12/04/2034 EU $14.81M 1.09%
US TREASURY N/B $14.64M 1.08%
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Allocation by sector

As of March 31, 2026 · N-PORT
View portfolio breakdown →

Portfolio moves

Dec 31, 2025 → Mar 31, 2026
Opened
128
Exited
108
Increased
39
Decreased
304
Unchanged
600

How many positions this fund opened, exited, grew, trimmed, or left unchanged between its two most recent N-PORT snapshots — net changes between point-in-time reports, not a trade log.

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FundOverlapNet exp.
PIMCO Diversified Income Fund · PDIIX, PDAAX, PDVAX, PDICX, PDVPX, PDNIX 31% 0.79%
PIMCO Multisector Bond Active Exchange-Traded Fund 17% 0.64%
Mercer Opportunistic Fixed Income Fund · MOFAX, MOFTX, MOFYX, MOFIX 16% 0.51%
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Advisers

As of December 31, 2025 · N-CEN
FirmRole
Pacific Investment Management Company LLC Sub-adviser
Mason Street Advisors, LLC Adviser

Footnotes

  1. Net assets and holdings count as of March 31, 2026, from the fund's N-PORT filing.

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