FLEXIBLE PAYMENT VARIABLE ANNUITY

Transcription

1 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY May 1, 2017 GO PAPERLESS! See back cover for details. FLEXIBLE PAYMENT VARIABLE ANNUITY Account B Individual flexible payment variable annuity contracts for: Individual Retirement Annuities (IRAs) Roth IRAs SIMPLE IRAs Simplified Employee Pension Plan IRAs 457 Deferred Compensation Plan Annuities Tax Deferred Annuities Non-Transferable Annuities Non-Tax Qualified Annuities PROSPECTUSES Flexible Payment Variable Annuity Account B Northwestern Mutual Series Fund, Inc. Fidelity VIP Mid Cap Portfolio Service Class 2 Fidelity VIP Contrafund Portfolio Service Class 2 Neuberger Berman AMT Socially Responsive Portfolio Russell Investment Funds Russell Investment Funds LifePoints Variable Target Portfolio Series Credit Suisse Trust Commodity Return Strategy Portfolio (0386)

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3 Northwestern Mutual Series Fund, Inc. Large Cap Blend Portfolio Supplement Dated February 7, 2018 to the Summary Prospectus for the Large Cap Blend Portfolio Dated May 1, 2017 The following information supplements the Summary Prospectus for the Large Cap Blend Portfolio of Northwestern Mutual Series Fund, Inc. dated May 1, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Portfolio Manager Update Effective January 31, 2018, Benjamin D. Karek joined Patrick J. English, John S. Brandser, Jonathan T. Bloom, Andy P. Ramer, Matthew J. Goetzinger, Robert M. Helf, Daniel G. Sievers, Matthew T. Sullivan and Jordan S. Teschendorf as co-portfolio managers of the Large Cap Blend Portfolio (the Portfolio ). Accordingly, the Portfolio Managers information set forth in the Summary Section for the Portfolio in the Prospectus under PORTFOLIO MANAGEMENT is hereby deleted and replaced with the following: Portfolio Managers: FMI s investment decisions are made by a Portfolio Management Committee (PMC). The investment process employed by the PMC is team based, and the PMC as a whole, not any individual member, is primarily responsible for the day-to-day management of the Portfolio. The PMC has managed the Portfolio since PMC members include: Patrick J. English, CFA, Chairman, Chief Executive Officer and Chief Investment Officer, who has been with FMI since John S. Brandser, President, Chief Operating Officer and Chief Compliance Officer, who has been with FMI since Jonathan T. Bloom, CFA, Director of Research, who has been with FMI since Andy P. Ramer, CFA, Research Analyst, who has been with FMI since Matthew J. Goetzinger, CFA, Research Analyst, who has been with FMI since Robert M. Helf, CFA, Research Analyst, who has been with FMI since Daniel G. Sievers, CFA, Research Analyst, who has been with FMI since Matthew T. Sullivan, CFA, Research Analyst, who has been with FMI since Jordan S. Teschendorf, CFA, Research Analyst, who has been with FMI since Benjamin D. Karek, Research Analyst, who has been with FMI since Please retain this Supplement for future reference. Page 1 of 1

4 Northwestern Mutual Series Fund, Inc. International Growth Portfolio Supplement Dated January 11, 2018 to the Summary Prospectus for the International Growth Portfolio Dated May 1, 2017 The following information supplements the Summary Prospectus for the International Growth Portfolio of Northwestern Mutual Series Fund, Inc. dated May 1, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Portfolio Manager Update Effective December 5, 2017, Jed Weiss returned from his leave of absence and has resumed sole responsibility as portfolio manager of the International Growth Portfolio (the Portfolio ). Accordingly, the Portfolio Manager information set forth in the Summary Section for the Portfolio in the Prospectus under PORTFOLIO MANAGEMENT is hereby deleted and replaced with the following: Portfolio Manager: Jed Weiss, Portfolio Manager, began managing the Portfolio in In addition, effective December 5, 2017, all information relating to Vincent Montemaggiore is deleted from the Prospectus. Please retain this Supplement for future reference. Page 1 of 1

5 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated December 21, 2017 to U.S. SMALL CAP EQUITY FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented December 21, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus and SAI, both dated May 1, 2017, as supplemented through December 21, 2017, and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus. II. MANAGEMENT: The following replaces the list of money managers in the sub-section entitled Management in the Summary Prospectus: Ancora Advisors, LLC Copeland Capital Management, LLC DePrince, Race & Zollo, Inc. Falcon Point Capital, LLC Penn Capital Management Company, Inc. Snow Capital Management L.P. Timpani Capital Management LLC

6 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated December 21, 2017 to INTERNATIONAL DEVELOPED MARKETS FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented September 14, 2017 and December 21, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus and SAI, both dated May 1, 2017, as supplemented through December 21, 2017, and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus. II. PRINCIPAL INVESTMENT STRATEGIES OF THE FUND: The following replaces the second paragraph sub-section entitled Principal Investment Strategies of the Fund in the Summary Prospectus: Russell Investment Management, LLC ( RIM ) provides or oversees the provision of all investment advisory and portfolio management services for the Fund, including developing the investment program for the Fund and managing the Fund's overall exposures. RIM employs a multi-style (growth, value, marketoriented and defensive) and multi-manager approach for the Fund whereby RIM selects the investment strategies for the Fund and utilizes multiple money managers to pursue those strategies. The Fund employs discretionary and non-discretionary money managers. The Fund s discretionary money managers select the individual portfolio instruments for the assets assigned to them. The Fund s non-discretionary money managers provide a model portfolio to RIM representing their investment recommendations, based upon which RIM purchases and sells securities for the Fund. RIM manages Fund assets not allocated to discretionary money managers, which include assets managed by RIM to effect the Fund's investment strategies and/or to actively manage the Fund's overall exposures to seek to achieve the desired risk/return profile for the Fund. RIM may utilize quantitative or qualitative analysis or quantitative models designed to assess Fund characteristics and identify a portfolio which provides the desired exposures or may use strategies based on indexes that represent the desired exposures, including index replication and optimized index sampling (strategies that seek to purchase the securities in an index or a sampling of securities using optimization and risk models, respectively). RIM also manages the portion of Fund assets for which the Fund's non-discretionary money managers provide model portfolios and the Fund's cash balances. The Fund usually, but not always, pursues a strategy to be fully invested by exposing all or a portion of its cash to the performance of appropriate markets by purchasing equity securities and/or derivatives, which typically include index futures contracts and forward currency contracts. The Fund may use derivatives, including stock options, country index futures and swaps or currency forwards, to (1) manage country and currency exposure as a substitute for holding securities directly or (2) facilitate the implementation of its investment strategy. The Fund may use derivatives to take both long and short positions. III. PRINCIPAL RISKS OF INVESTING IN THE FUND: The following risk factor is added to the subsection entitled Principal Risks of Investing in the Fund in the Summary Prospectus: Non-Discretionary Implementation Risk. With respect to the portion of the Fund that is managed pursuant to model portfolios provided by non-discretionary money managers, it is expected that trades will be effected on a periodic basis and therefore less frequently than would typically be the case if discretionary money managers were employed. Given that values of investments change with market conditions, this could cause the Fund's return to be lower than if the Fund employed discretionary money managers with respect to that portion of its portfolio.

7 IV. MANAGEMENT: The following replaces the list of money managers in the sub-section entitled Management in the Summary Prospectus: GQG Partners LLC Janus Capital Management LLC and Perkins Investment Management LLC Numeric Investors LLC Pzena Investment Management, LLC Wellington Management Company LLP

8 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated December 21, 2017 to STRATEGIC BOND FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented December 21, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus and SAI, both dated May 1, 2017, as supplemented through December 21, 2017, and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus. II. INVESTMENT OBJECTIVE: The following replaces the Investment Objective in the sub-section entitled Investment Objective in the Summary Prospectus: Through February 28, 2018, the Fund seeks to provide current income, and as a secondary objective, capital appreciation. Effective March 1, 2018, the Fund seeks to provide total return.

9 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated December 21, 2017 to MODERATE STRATEGY FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented December 21, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus, dated May 1, 2017, as supplemented through December 21, 2017, SAI dated May 1, 2017, as supplemented through September 14, 2017 and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus.

10 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated December 21, 2017 to BALANCED STRATEGY FUND GROWTH STRATEGY FUND EQUITY GROWTH STRATEGY FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented September 14, 2017 and December 21, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus, dated May 1, 2017, as supplemented through December 21, 2017, SAI dated May 1, 2017, as supplemented through September 14, 2017 and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus.

11 Northwestern Mutual Series Fund, Inc. Select Bond Portfolio Supplement Dated December 15, 2017 to the Summary Prospectus for the Select Bond Portfolio Dated May 1, 2016 The following information supplements the Summary Prospectus for the Select Bond Portfolio of Northwestern Mutual Series Fund, Inc. dated May 1, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Portfolio Managers Update Effective October 16, 2017, Maulik Bhansali and Jarad Vasquez joined Troy Ludgood and Thomas O'Connor as co-portfolio managers of the Select Bond Portfolio (the Portfolio ). Accordingly, the Portfolio Managers information set forth in the PORTFOLIO MANAGEMENT section is hereby deleted and replaced with the following: Portfolio Managers: Troy Ludgood, Senior Portfolio Manager at WellsCap, has been with WellsCap since 2004 and has co-managed the Portfolio since Thomas O Connor, CFA, Senior Portfolio Manager at WellsCap, has been with WellsCap since 2000 and has co-managed the Portfolio since Maulik Bhansali, CFA, Senior Portfolio Manager at WellsCap, has been with WellsCap since 2001 and has co-managed the Portfolio since October Jarad Vasquez, Senior Portfolio Manager at WellsCap, has been with WellsCap since 2007 and has co-managed the Portfolio since October In addition, Mr. Ludgood plans to transition to a new role effective April 30, 2018 and will no longer serve as a coportfolio manager of the Portfolio after such date. Accordingly, effective April 30, 2018, all information relating to Mr. Ludgood is deleted from the Prospectus. Please retain this Supplement for future reference. Northwestern Mutual Series Fund, Inc. Select Bond Portfolio Supplement Dated December 18, 2017 to the Summary Prospectus for the Select Bond Portfolio Dated May 1, 2017 The following information supplements the Summary Prospectus for the Select Bond Portfolio of Northwestern Mutual Series Fund, Inc. dated May 1, 2017, as supplemented December 15, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Revised Reference to Summary Prospectus Date The Summary Prospectus Supplement dated December 15, 2017 ("Supplement") contained a typographical error which incorrectly identified the date of the Summary Prospectus being supplemented as May 1, This date is hereby corrected so that the title information for the Supplement provides as follows: "Supplement Dated December 15, 2017 to the Summary Prospectus for the Select Bond Portfolio Dated May 1, 2017." Please retain this Supplement for future reference.

12 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated September 14, 2017 to INTERNATIONAL DEVELOPED MARKETS FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented September 14, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus and SAI, both dated May 1, 2017, as supplemented through September 14, 2017, and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus. II. PERFORMANCE: The following is added at the end of the second paragraph in the sub-section entitled Performance in the Summary Prospectus: Effective January 1, 2018, RIM will change the Fund s primary benchmark from the Russell Developed ex- US Large Cap Index (net of tax on dividends from foreign holdings) to the MSCI World ex USA Index (net of tax on dividends from foreign holdings). RIM believes that the MSCI World ex USA Index (net of tax on dividends from foreign holdings) more accurately provides a means to compare the Fund's average annual total returns to a benchmark that currently best represents the investable global and international equity markets.

13 Russell Investment Funds RUSSELL INVESTMENT FUNDS Supplement dated September 14, 2017 to BALANCED STRATEGY FUND GROWTH STRATEGY FUND EQUITY GROWTH STRATEGY FUND SUMMARY PROSPECTUS DATED May 1, 2017, As supplemented September 14, 2017 I. SUMMARY PROSPECTUS LEGEND: The legend appearing at the top of the first page of the Summary Prospectus is hereby replaced with the following: Before you invest, you may want to review the Fund s Prospectus, which contains more information about the Fund and its risks. You can find the Fund s Prospectus, Statement of Additional Information (SAI), Annual Report and other information about the Fund online at You can also get this information at no cost by calling or by sending an to: service@russellinvestments.com. The Fund s Prospectus and SAI, both dated May 1, 2017, as supplemented through September 14, 2017, and the Fund s most recent shareholder report, dated June 30, 2017, are all incorporated by reference into this Summary Prospectus. II. PERFORMANCE: The following is added at the end of the second paragraph in the sub-section entitled Performance in the Summary Prospectus: Effective January 1, 2018, RIM will change the Fund s secondary benchmark from the Russell Developed ex-us Large Cap Index (net of tax on dividends from foreign holdings) to the MSCI World ex USA Index (net of tax on dividends from foreign holdings). RIM believes that the MSCI World ex USA Index (net of tax on dividends from foreign holdings) more accurately provides a means to compare the Fund s average annual total returns to a benchmark that currently best represents the investable global and international equity markets.

14 Northwestern Mutual Series Fund, Inc. Large Cap Core Stock Portfolio Supplement Dated September 27, 2017 to the Summary Prospectus for the Large Cap Core Stock Portfolio Dated May 1, 2017 The following information supplements the Summary Prospectus for the Large Cap Core Stock Portfolio of Northwestern Mutual Series Fund, Inc. ( Fund ) dated May 1, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Sub-Adviser Change On or about October 27, 2017, Wellington Management Company LLP ( Wellington Management ) will replace Fayez Sarofim & Co. as the sub-adviser for the Fund s Large Cap Core Stock Portfolio (the Portfolio ). Wellington Management will provide investment sub-advisory services for the Portfolio pursuant to an Investment Sub-Advisory Agreement approved by the Fund s Board of Directors on August 15, In approving the Investment Sub-Advisory Agreement, the Fund relied on an Exemptive Order issued by the Securities and Exchange Commission that permits the Fund and its investment adviser to hire or terminate a subadviser at any time without shareholder approval so long as, among other conditions, shareholders are provided notice of the change. As a result of this change, the Summary Prospectus shall be amended effective October 27, 2017 as noted below. The PRINCIPAL INVESTMENT STRATEGIES section is amended to read as follows: Normally, the Portfolio invests at least 80% of net assets (plus any borrowings for investment purposes) in equity securities of large capitalization companies. For this purpose, large capitalization equity investments are those whose market capitalizations are above $5 billion at the time of purchase. In managing the Portfolio, the adviser allocates the Portfolio s assets across a variety of industries, selecting companies in each industry based on the research of a team of global industry analysts. The Portfolio typically seeks to maintain representation in each major industry represented by broad-based, large cap U.S. equity indices. In analyzing a prospective investment for the Portfolio, the adviser utilizes a bottom-up approach, which is the use of fundamental analysis to identify specific securities for purchase or sale. Fundamental analysis of a company involves the assessment of a variety of factors, including the company s business environment, management quality, balance sheet, income statement, anticipated earnings, revenues and dividends, and other related measures or indicators of valuation and growth potential. The Portfolio s sector exposures generally conform with the sector weights present in the Portfolio s benchmark index and as a result, in combination with the Portfolio s reliance on fundamental company analysis, and based upon market or economic conditions, the Portfolio may at times have a relatively high percentage of its assets invested in a particular sector of the market. Page 1 of 2

15 The Portfolio invests primarily in U.S. common stocks. Up to 20% of the Portfolio s net assets may be invested in foreign based companies listed on foreign exchanges, either directly or through American Depositary Receipts (ADRs). The Portfolio may sell a security for a variety of reasons, including a significant adverse change in the company s business fundamentals, if the company has become significantly overvalued in terms of earnings, assets or growth prospects, or more attractive alternatives exist. The PERFORMANCE section is amended by inserting the following as the third and fourth sentences of the first paragraph: Prior to October 27, 2017, the sub-adviser to the Portfolio was different. Performance shown may have been different if the current strategy, and the current sub-adviser, had been in place during the periods shown. The PORTFOLIO MANAGEMENT section is amended to read as follows: Investment Adviser: Mason Street Advisors, LLC (MSA) Sub-Adviser: Wellington Management Company LLP (Wellington Management) Portfolio Managers: Mark D. Mandel, CFA and Director of Global Industry Research, joined Wellington Management in 1995 and has co-managed the Portfolio since October Jonathan G. White, CFA and Director of Research Portfolios, joined Wellington Management in 1999 and has co-managed the Portfolio since October The Portfolio may experience increased portfolio turnover over the short term in connection with the transition to a new sub-adviser. Increased portfolio turnover can result in higher brokerage commissions and other transaction costs, which can adversely affect performance. Please retain this Supplement for future reference. Page 2 of 2

16 Northwestern Mutual Series Fund, Inc. Mid Cap Growth Stock Portfolio Supplement Dated September 27, 2017 to the Summary Prospectus for the Mid Cap Growth Stock Portfolio Dated May 1, 2017 The following information supplements the Summary Prospectus for the Mid Cap Growth Stock Portfolio of Northwestern Mutual Series Fund, Inc. ( Fund ) dated May 1, 2017 (the Summary Prospectus ), a copy of which you have already received. You should read this Supplement together with the Summary Prospectus. Sub-Adviser Change On or about October 27, 2017, Wellington Management Company LLP ( Wellington Management ) will replace William Blair Investment Management, LLC as the sub-adviser for the Fund s Mid Cap Growth Stock Portfolio (the Portfolio ). Wellington Management will provide investment sub-advisory services for the Portfolio pursuant to an Investment Sub-Advisory Agreement approved by the Fund s Board of Directors on August 15, In approving the Investment Sub-Advisory Agreement, the Fund relied on an Exemptive Order issued by the Securities and Exchange Commission that permits the Fund and its investment adviser to hire or terminate a sub-adviser at any time without shareholder approval so long as, among other conditions, shareholders are provided notice of the change. As a result of this change, the Summary Prospectus shall be amended effective October 27, 2017 as noted below. The PRINCIPAL INVESTMENT STRATEGIES section is amended to read as follows: Normally, the Portfolio invests at least 80% of net assets (plus any borrowings for investment purposes) in stocks of mid-sized companies. The Portfolio considers a company to be a midcapitalization company if it has a market capitalization within the collective range of the Russell MidCap Index and the S&P MidCap 400 Index. As of June 30, 2017, this range was approximately $1.2 billion to $47.2 billion. The market capitalization range of these indices changes over time. Securities of companies whose market capitalizations no longer fall within this collective range after purchase may continue to be held by the Portfolio. The Portfolio invests primarily in common stocks of mid cap companies selected on the basis of their potential for capital appreciation. The Portfolio focuses on companies that are determined to be of high quality. The key characteristics of high quality companies include a leadership position within an industry, a strong balance sheet, a high return on equity, and/or a strong management team. The Portfolio seeks to reduce overall risk by diversifying across sectors, industry groups and companies. The Portfolio s sector exposure relative to its benchmark is driven by an investment process which relies on fundamental company analysis and individual stock selection. As a result, based upon market or economic conditions, the Portfolio may at times have a relatively high percentage of its assets invested in a particular sector of the market. Page 1 of 2

17 The Portfolio invests primarily in U.S. common stocks. The Portfolio may also invest up to 20% of net assets in American Depositary Receipts (ADRs) and other securities of foreign issuers, including non-u.s. dollar denominated securities. The Portfolio typically trims positions as valuation appears incrementally less attractive, and may sell a stock when the adviser s investment thesis is no longer valid, typically due to an erosion of company fundamentals relative to expectations or when valuation is no longer attractive. The Portfolio may, but is not required to, exit a position if the company s capitalization grows beyond the mid cap range. The PRINCIPAL RISKS section is amended by adding the following Foreign Currency Risk factor: Foreign Currency Risk The risk that foreign (non-u.s. dollar) currency denominated securities may be adversely affected by decreases in foreign currency values relative to the U.S. dollar. Investments in securities subject to foreign currency risk may have more rapid and extreme changes in value or more losses than investments in U.S. dollar denominated securities. The PERFORMANCE section is amended by inserting the following as the third and fourth sentences of the first paragraph: Prior to October 27, 2017, the sub-adviser to the Portfolio was different. Performance shown may have been different if the current strategy, and the current sub-adviser, had been in place during the periods shown. The PORTFOLIO MANAGEMENT section is amended to read as follows: Investment Adviser: Mason Street Advisors, LLC (MSA) Sub-Adviser: Wellington Management Company LLP (Wellington Management) Portfolio Managers: Philip W. Ruedi, CFA, Senior Managing Director and Equity Portfolio Manager, joined Wellington Management in 2004 and has co-managed the Portfolio since October Mark Whitaker, CFA, Senior Managing Director and Equity Portfolio Manager, joined Wellington Management in 2004 and has co-managed the Portfolio since October The Portfolio may experience increased portfolio turnover over the short term in connection with the transition to a new sub-adviser. Increased portfolio turnover can result in higher brokerage commissions and other transaction costs, which can adversely affect performance. Please retain this Supplement for future reference. Page 2 of 2

18 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY Supplement dated August 21, 2017 PROSPECTUSES DATED MAY 1, 2017 NML VARIABLE ANNUITY ACCOUNT A SUPPLEMENT TO THE PROSPECTUSES FLEXIBLE PAYMENT VARIABLE ANNUITY INDIVIDUAL FLEXIBLE PAYMENT VARIABLE ANNUITY (FEE-BASED) NML VARIABLE ANNUITY ACCOUNT B SUPPLEMENT TO THE PROSPECTUSES FLEXIBLE PAYMENT VARIABLE ANNUITY FLEXIBLE PAYMENT VARIABLE ANNUITY (FEE-BASED) NML VARIABLE ANNUITY ACCOUNT C SUPPLEMENT TO THE PROSPECTUSES GROUP COMBINATION ANNUITY INDIVIDUAL FLEXIBLE PAYMENT VARIABLE ANNUITY (NETWORK EDITION) This Supplement amends certain information contained in the Prospectuses referenced above. 1. On or about October 27, 2017, in the section titled, Investment Options-Variable Options Northwestern Mutual Series Fund, Inc. in the Account A Flexible Payment Variable Annuity and Individual Flexible Payment Variable Annuity (Fee-Based) Prospectuses, the Account B Flexible Payment Variable Annuity and Flexible Payment Variable Annuity (Fee-Based) Prospectuses, and the Account C Group Combination Annuity Prospectus; and, in the section titled Investment Options - Northwestern Mutual Series Fund, Inc. in the Account C Network Edition Prospectus, the following table is amended to contain the following information for the Mid Cap Growth Stock and Large Cap Core Stock Portfolios: Portfolio Investment Objective Sub-adviser (if applicable) Mid Cap Growth Stock Portfolio Long-term growth of capital Wellington Management Company LLP Long-term growth of capital and Large Cap Core Stock Portfolio income Wellington Management Company LLP Please read this Supplement carefully and keep it with your Prospectus for future reference. This Supplement is dated August 21, 2017.

19 Northwestern Mutual Series Fund, Inc. Prospectus Supplement Dated August 18, 2017 The following information supplements the Statutory Prospectus for the Northwestern Mutual Series Fund, Inc. (the Fund ) dated May 1, 2017, as supplemented May 24, 2017 (the Prospectus ). You should read this Supplement together with the Prospectus. Sub-Adviser Changes for Mid Cap Growth Stock and Large Cap Core Stock Portfolios On or about October 27, 2017, Wellington Management Company LLP ( Wellington Management ) will replace William Blair Investment Management, LLC as the sub-adviser for the Fund s Mid Cap Growth Stock Portfolio and will also replace Fayez Sarofim & Co. as the sub-adviser for the Fund s Large Cap Core Stock Portfolio. Wellington Management will provide investment subadvisory services for the Portfolios pursuant to Investment Sub-Advisory Agreements approved by the Fund s Board of Directors on August 15, In approving the new Investment Sub-Advisory Agreements, the Fund relied on an Exemptive Order issued by the Securities and Exchange Commission that permits the Fund and its investment adviser to hire or terminate a sub-adviser at any time without shareholder approval so long as, among other conditions, shareholders are provided notice of the change. Additional information about Wellington Management, its investment strategies for the Portfolios, associated risks, and other information will be made available in the coming months consistent with the requirements of the Exemptive Order. Please retain this Supplement for future reference.

20 Northwestern Mutual Series Fund, Inc. Prospectus Supplement Dated May 24, 2017 The following information supplements the Statutory Prospectus for the Northwestern Mutual Series Fund, Inc. (the Fund ) dated May 1, 2017 (the Prospectus ). You should read this Supplement together with the Prospectus. Amendments to Investment Sub-Advisory Agreements with Certain Sub-Advisers Effective February 22, 2017, the Board of Directors of the Fund approved amended and restated investment sub-advisory agreements between Mason Street Advisors, LLC ( Mason Street Advisors ) and (i) The Boston Company Asset Management, LLC ( The Boston Company ) with respect to the Growth Stock Portfolio; (ii) William Blair Investment Management, LLC ( William Blair ) with respect to the Mid Cap Growth Stock Portfolio; and (iii) Wellington Management Company LLP ( Wellington ) with respect to the Small Cap Growth Portfolio. Effective May 10, 2017, the Board of Directors of the Fund approved amended and restated investment sub-advisory agreements between Mason Street Advisors and (i) Fayez Sarofim & Co. ( Sarofim & Co. ) with respect to the Large Cap Core Stock Portfolio; (ii) FIAM LLC ( FIAM ) with respect to the International Growth Portfolio; (iii) Fiduciary Management, Inc. ( FMI ) with respect to the Large Cap Blend Portfolio; (iv) Massachusetts Financial Services Company ( MFS ) with respect to the Research International Core Portfolio; and (v) Templeton Investment Counsel, LLC ( Templeton ) with respect to the International Equity Portfolio. In approving the foregoing amended and restated investment sub-advisory agreements (the Amended Agreements ), the Fund relied on an Exemptive Order issued by the Securities and Exchange Commission that permits the Fund and Mason Street Advisors to amend investment sub-advisory agreements without shareholder approval so long as, among other conditions, shareholders are provided notice of the amendment. The Amended Agreements, which conform the existing agreements with The Boston Company, William Blair, Wellington, Sarofim & Co., FIAM, FMI, MFS and Templeton to Mason Street Advisors current form of Investment Sub-Advisory Agreement, include updated provisions reflecting developments in the investment management industry and memorializing certain business practices in place between Mason Street Advisors and its sub-advisers. The Amended Agreements include certain reporting and monitoring obligations applicable to investments in commodity interests, particularly involving derivatives transactions. The Amended Agreements also set forth the sub-advisers responsibilities regarding the establishment and implementation of a reasonably-designed cybersecurity program and associated policies. Except for a modification regarding the fee schedule applicable to the Large Cap Blend Portfolio managed by FMI, the Amended Agreements did not include any changes to fees. Please retain this Supplement for future reference.

21 Table of Contents Variable Product Prospectus Page Label Flexible Payment Variable Annuity Account B 1 Summary Prospectuses Northwestern Mutual Series Fund, Inc. Growth Stock Portfolio Focused Appreciation Portfolio Large Cap Core Stock Portfolio Large Cap Blend Portfolio Index 500 Stock Portfolio Large Company Value Portfolio Domestic Equity Portfolio Equity Income Portfolio Mid Cap Growth Stock Portfolio Index 400 Stock Portfolio Mid Cap Value Portfolio Small Cap Growth Stock Portfolio Index 600 Stock Portfolio Small Cap Value Portfolio International Growth Portfolio Research International Core Portfolio International Equity Portfolio Emerging Markets Equity Portfolio Government Money Market Portfolio Short-Term Bond Portfolio Select Bond Portfolio Long-Term U.S. Government Bond Portfolio Inflation Protection Portfolio High Yield Bond Portfolio Multi-Sector Bond Portfolio Balanced Portfolio Asset Allocation Portfolio Fidelity Variable Insurance Products VIP Mid Cap Portfolio VIP Contrafund Portfolio Neuberger Berman Advisers Management Trust Socially Responsive Portfolio Russell Investment Funds U.S. Strategic Equity Fund U.S. Small Cap Equity Fund Global Real Estate Securities Fund International Developed Markets Fund Strategic Bond Fund Russell Investment Funds LifePoints Variable Target Portfolio Series Moderate Strategy Fund Balanced Strategy Fund Growth Strategy Fund Equity Growth Strategy Fund Credit Suisse Trust Commodity Return Strategy Portfolio Page Label NMSF-1 NMSF-4 NMSF-7 NMSF-10 NMSF-13 NMSF-16 NMSF-19 NMSF-22 NMSF-25 NMSF-28 NMSF-31 NMSF-34 NMSF-38 NMSF-41 NMSF-45 NMSF-48 NMSF-52 NMSF-55 NMSF-59 NMSF-62 NMSF-66 NMSF-69 NMSF-73 NMSF-77 NMSF-80 NMSF-85 NMSF-90 Page Label FI-1 FI-7 Page Label NB-1 Page Label RIF-1 RIF-7 RIF-13 RIF-19 RIF-25 Page Label RLP-1 RLP-9 RLP-17 RLP-25 Page Label CST-1

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23 Prospectus May 1, 2017 Flexible Payment Variable Annuity Issued by The Northwestern Mutual Life Insurance Company and NML Variable Annuity Account B This prospectus describes an individual flexible payment variable annuity contract (the Contract ) for: Individual Retirement Annuities ( IRAs ) Roth IRAs Simple IRAs Simplified Employee Pension Plan IRAs 457 Deferred Compensation Plan Annuities Tax Deferred Annuities Non-Transferable Annuities Non-Tax Qualified Annuities The Contract provides for accumulation of Contract Value on a variable and/or a fixed basis and a payment of annuity benefits on a fixed or variable basis. Net Purchase Payments may be invested, pursuant to the Contract, in the following variable and fixed options: Northwestern Mutual Series Fund, Inc. Growth Stock Portfolio Focused Appreciation Portfolio Large Cap Core Stock Portfolio Large Cap Blend Portfolio Index 500 Stock Portfolio Large Company Value Portfolio Domestic Equity Portfolio Equity Income Portfolio Mid Cap Growth Stock Portfolio Index 400 Stock Portfolio Mid Cap Value Portfolio Small Cap Growth Stock Portfolio Index 600 Stock Portfolio Small Cap Value Portfolio International Growth Portfolio Research International Core Portfolio International Equity Portfolio Emerging Markets Equity Portfolio Government Money Market Portfolio Short-Term Bond Portfolio Select Bond Portfolio Long-Term U.S. Government Bond Portfolio Inflation Protection Portfolio High Yield Bond Portfolio Multi-Sector Bond Portfolio Balanced Portfolio Asset Allocation Portfolio Variable Options Fidelity Variable Insurance Products VIP Mid Cap Portfolio VIP Contrafund Portfolio Neuberger Berman Advisers Management Trust Socially Responsive Portfolio Russell Investment Funds U.S. Strategic Equity Fund U.S. Small Cap Equity Fund Global Real Estate Securities Fund International Developed Markets Fund Strategic Bond Fund Russell Investment Funds LifePoints Variable Target Portfolio Series Moderate Strategy Fund Balanced Strategy Fund Growth Strategy Fund Equity Growth Strategy Fund Credit Suisse Trust Commodity Return Strategy Portfolio Fixed Options Guaranteed Interest Fund 1 Guaranteed Interest Fund 8 The Contract (including the fixed options) and the variable options are not guaranteed to achieve their goals, are not bank deposits, are not federally insured, and are not endorsed by any bank or government agency. You could lose the money you invest in this Contract. All contractual guarantees (including the fixed options) are contingent upon the claims-paying ability of the Company. Please read carefully this prospectus and the accompanying prospectuses for the variable options and keep them for future reference. These prospectuses provide information that you should know before investing in the Contract. No person is authorized to make any representation in connection with the offering of the Contract other than those contained in these prospectuses. The Securities and Exchange Commission ( SEC ) 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 Contract may not be available in all states and is only offered where it can be lawfully sold. Our Distributor may limit sales of the Contract to certain government entities and government entity plans. More information about the Contract and NML Variable Annuity Account B (the Separate Account ) is included in a Statement of Additional Information ( SAI ), dated May 1, 2017, which is incorporated by reference in this prospectus and available free of charge from The Northwestern Mutual Life Insurance Company. The table of contents for the SAI is at the end of this prospectus. The SAI is available free of charge at To receive a copy of the SAI, send a written request to Northwestern Mutual, Life and Annuity Products Department, Room 2E450, 720 East Wisconsin Avenue, Milwaukee, WI Information about the Separate Account (including the SAI) is available on the SEC s internet site at or may be obtained, upon payment of a duplicating fee, by writing the Public Reference Section of the SEC, 100 F Street, NE, Washington, DC This information can also be reviewed and copied at the SEC s Public Reference Room in Washington, D.C. For information on the Public Reference Room s operation, call the SEC at

24 Contents of this Prospectus Page GLOSSARY OF SPECIAL TERMS... 1 FEE AND EXPENSE TABLES... 2 Contract Fees and Expenses... 2 Range of Total Annual Portfolio Operating Expenses... 3 Examples... 3 CONDENSED FINANCIAL INFORMATION... 4 THE COMPANY... 4 THE SEPARATE ACCOUNT... 5 THE INVESTMENT OPTIONS... 5 Variable Options... 6 Northwestern Mutual Series Fund, Inc Fidelity Variable Insurance Products... 7 Neuberger Berman Advisers Management Trust... 7 Russell Investment Funds... 7 Credit Suisse Trust... 8 Payments We Receive... 8 Transfers Between Divisions... 8 Short Term and Excessive Trading... 9 Fixed Options Moving into a Guaranteed Account Moving out of a Guaranteed Account Withdrawal Charge Market Value Adjustment (GIF 8 Only) GIF 8 Market Value Adjustment Example Additional Information Preservation+ Strategy THE CONTRACT Generally Free Look Contract Values Purchase Payments Under the Contract Frequency and Amount Guaranteed Account Investment Minimums and Maximums Application of Purchase Payments Reduction or Waiver of Certain Charges Maturity Date Gender-Based Annuity Payment Rates Reinvestment of Redemptions Access to Your Money Withdrawals Page Benefits Provided Under the Contracts Death Benefit How Much is the Death Benefit? When is the Death Benefit Determined? Guaranteed Minimum Death Benefit Examples Enhanced Death Benefit Examples How is the Death Benefit Distributed? Income Plans Generally Description of Variable Income Plans Amount of Annuity Payments Assumed Investment Rate DEDUCTIONS Sales Load Contract Fee Mortality Rate and Expense Risk Charges Nature and Amount of the Charges Reduction of the Charges Other Expense Risks Withdrawal Charges Withdrawal Charge Rates Waiver of Withdrawal Charges Withdrawal Charges and Our Distribution Expenses Special Withdrawal Charges and Rules Applicable to Guaranteed Accounts Other Charges Enhanced Death Benefit Charge Premium Taxes Portfolio Expenses and Charges Expedited Delivery Charge FEDERAL INCOME TAXES Qualified and Non-Tax Qualified Plans Contribution Limitations and General Requirements Applicable to Contracts Traditional IRA Roth IRA SEP Simple IRA Tax Deferred Annuity Section 457 Plan Nontransferable Annuity Non-Tax Qualified Contract... 24

25 Contents of this Prospectus Page Taxation of Contract Benefits IRAs, SEPs, SIMPLE IRAs, TDAs and Section 457 Plans and Nontransferable Annuities Roth IRAs Nonqualified Contracts Premature Withdrawals Minimum Distribution Requirements Mandatory Withholding Taxation of Northwestern Mutual Other Considerations CONTRACT OWNER SERVICES Automatic Dollar-Cost Averaging Electronic Funds Transfer ( EFT ) Systematic Withdrawal Plan Automatic Required Minimum Distributions ( RMD ) Special Withdrawal Privilege Portfolio Rebalancing Interest Sweeps Substitution of Portfolio Shares and Other Changes Page Owner Inquiries and Instructions Householding Allocation Models ADDITIONAL INFORMATION The Distributor Terminal Illness Benefit Nursing Home Benefit Voting Rights Dividends Dividends for Contracts Issued Prior to March 31, Internal Annuity Exchanges Speculative Investing Abandoned Property Requirements Cybersecurity Legal Proceedings TABLE OF CONTENTS FOR STATEMENT OF ADDITIONAL INFORMATION APPENDIX A PRIOR CONTRACTS APPENDIX B ACCUMULATION UNIT VALUES This prospectus describes only the Separate Account and the variable provisions of the Contracts, except where there are specific references to the fixed provisions.

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27 Glossary of Special Terms Unless otherwise specified in this prospectus, the words Northwestern Mutual, we, us, our, and Company mean The Northwestern Mutual Life Insurance Company. The words you and your, unless otherwise specified, mean the Contract Owner. We use a number of special terms in this prospectus, including the following: Accumulation Unit An accounting unit of measure representing the Contract Value, before the date on which Annuity Payments begin, in one or more Divisions of the Separate Account. The related term Accumulation Unit Value means the value of a particular Accumulation Unit at a particular time and is analogous to, but not the same as, the share price of a mutual fund. Annuitant The person upon whose life the Contract is issued and Contract benefits depend. The Primary Annuitant is the person upon whose life the Contract is initially issued. The Contingent Annuitant is the person who becomes the Annuitant upon the death of the Primary Annuitant. Annuity Payments Money we pay pursuant to the terms of the Contract. Payments may be paid under one or more of the following three methods: (1) a variable income plan; (2) a fixed income plan; or (3) in cash. Annuity Unit An accounting unit of measure representing the actuarial value of a variable income plan s interest in a Division of the Separate Account after Annuity Payments begin. Beneficiary A person who receives payments under the Contract upon the death of the Annuitant before the Maturity Date provided that the Annuitant was an Owner of the Contract at the time of death. Contract The agreement between you and us described in this variable annuity prospectus. During the Accumulation Period of the Contract, you may invest and any earnings on your investment will accumulate on a tax-deferred basis. During the Annuitization Period, you receive periodic payments based largely on the amounts you accumulate, all or a portion of which will be taxable as ordinary income. Contract Value The value of your Contract on any Valuation Date is the sum of: (1) the value of your amounts held in the Divisions of the Separate Account on that Valuation Date; and (2) the sum of your amounts allocated to any Guaranteed Account, plus credited interest; less (3) any withdrawals from any Guaranteed Account and any applicable Market Value Adjustment or charges under the Contract deducted from any Guaranteed Account. Division A sub-account of the Separate Account, the assets of which are invested exclusively in the shares of one of the Portfolios of the underlying Funds. Fund A Fund is registered under the Investment Company Act of 1940 (the 1940 Act ) as an open-end management investment company or as a unit investment trust, or is not required to be registered under the 1940 Act. A Fund is available as an investment option under the Contract. The assets of each of the Divisions of the Separate Account are used to purchase shares of the corresponding Portfolio of a Fund. General Account All assets of the Company, other than those held in the Separate Account or in other separate accounts that have been or may be established by the Company. Guaranteed Account A fixed investment option under the Contract, supported by the assets held in the Company s General Account, that has a term of a specified duration (called a Guaranteed Period ). Income Plan An optional method of receiving the death benefit, maturity benefit, surrender proceeds or withdrawal proceeds of an insurance policy or annuity contract through a series of periodic payments. An Income Plan may also be known as a payment plan. Market Value Adjustment An amount that may be credited (or charged) upon a withdrawal from a multi-year Guaranteed Account before the end of a Guaranteed Period. Maturity Date The date, stated on the specifications page of the Contract, on which Purchase Payments cease and Annuity Payments become payable. Owner The person with the sole right to exercise all rights and privileges under the Contract, except as the Contract otherwise provides. Portfolio A series of a Fund available for investment under the Contract which corresponds to a particular Division of the Separate Account. Purchase Payments Money you give us to apply to your Contract. The related term Net Purchase Payment refers to Purchase Payments after all applicable deductions. Required Minimum Distribution ( RMD ) A minimum amount that federal tax law generally requires be withdrawn from certain tax-qualified annuities each year. Separate Account The account the Company has established pursuant to Wisconsin law for those assets, although belonging to the Company, that are reserved for you and other owners of variable annuity contracts supported by the Separate Account. Valuation Date Any day on which the New York Stock Exchange ( NYSE ) is open for trading and any other day we are required under the 1940 Act to value assets of a Division of the Separate Account. This prospectus describes two versions of the Select Variable Annuity contract: a front-load version (in which a sales charge is assessed when purchase payments are made) and a backload version (in which a sales charge is assessed if and when amounts are withdrawn). Account B Prospectus 1