Thrivent Series Fund, Inc. Supplement to the Prospectus ...

1 Thrivent Series fund , to the Prospectusdated April 28, 2017with respect toThrivent Growth and Income Plus PortfolioThe Board of Directors of Thrivent Series fund , Inc. has approved the merger of Thrivent Growth and IncomePlus Portfolio (the Target Portfolio ) into Thrivent Moderately Aggressive Allocation Portfolio. The merger issubject to approval by contractholders of the Target Portfolio at a special meeting of contractholders to be heldon or about June 21, 2018. The merger, if approved by contractholders, will occur on or about June 28, 2018. TheTarget Portfolio and its corresponding subaccount will be closed as new investment selections at the end of theday on April 27, 2018.

2 If you already invest in a subaccount corresponding to the Target Portfolio, you cancontinue to invest in the subaccount until the merger has been date of this Supplement is March 5, include this Supplement with your Series fund , to the Prospectusdated April 28, 2017with respect toThrivent Small Cap Index PortfolioThrivent Mid Cap Index PortfolioThrivent Large Cap Index PortfolioBrian W. Bomgren, CQF and Sharon Wang, CFA, FRM have been named portfolio managers of Thrivent SmallCap Index Portfolio, Thrivent Mid Cap Index Portfolio, and Thrivent Large Cap Index Portfolio (together, the Portfolios ).

3 Mr. Bomgren has been with Thrivent Financial since 2006 and is currently a Senior EquityPortfolio Manager. Ms. Wang has been with Thrivent Financial since 2017 and is currently an IntermediateEquity Portfolio Manager. Prior to joining Thrivent Financial, Ms. Wang worked at Bryn Mawr CapitalManagement as a portfolio manager from R. Brimmer is no longer a portfolio manager for the Portfolios. As a result, all references to Mr. Brimmerare hereby removed from the date of this Supplement is January 19, include this Supplement with your Series fund , to Prospectusdated April 28, 2017with respect toThrivent Partner Healthcare PortfolioOn September 11, 2017, BlackRock Investment Management, LLC will replace Sectoral Asset Management the subadviser of Thrivent Partner Healthcare Portfolio (the Portfolio ).

4 As a result, the following changes tothe Prospectus will be made on that The third paragraph under Principal Strategies in the Summary Section will be deleted andreplaced with the following:BlackRock Investment Management, LLC, the Portfolio s subadviser, considers a variety offactors when choosing investments for the Portfolio, including (i) identifying companies andindustries that appear to have the potential for above-average returns; and (ii) identifyingcompanies that are expected to show above-average growth over the long-term, as well as thosethat appear to be trading below their true worth.

5 The Portfolio will generally sell a stock when, inthe opinion of the subadviser, the stock reaches its price target or if there is deterioration in thecompany s fundamentals, a change in macroeconomic outlook, technical deterioration, valuationissues, a need to rebalance the Portfolio or a better opportunity The second sentence under Investment Adviser(s) in the Summary Section will be deleted andreplaced with the following: Thrivent Financial has engaged BlackRock Investment Management, LLC to subadvise Information about the portfolio manager under Management Portfolio Manager(s) in the SummarySection and under Portfolio Management Thrivent Partner Healthcare Portfolio in the Management section will be deleted and replaced with the following:Erin Xie,Managing Director of BlackRock, Inc.

6 , has served as the portfolio manager of thePortfolio since 2017. Dr. Xie has been a Managing Director of BlackRock, Inc. since 2006 andjoined BlackRock, Inc. as a Director in 2005. Prior to joining BlackRock, Inc., Dr. Xie was aSenior Vice President of State Street Research & Management from 2001 to date of this Supplement is September 1, include this Supplement with your Series fund , to Prospectusdated April 28, 2017with respect toThrivent Bond Index PortfolioShareholders of Thrivent Bond Index Portfolio (the Portfolio ) approved the changes described below at ameeting held on August 10, 2017. The changes will be implemented on August 28, The Portfolio will change its name to Thrivent Government Bond The disclosure under Investment Objective in the Summary Section of the Prospectus will bedeleted and replaced with the following: Thrivent Government Bond Portfolio seeks total return, consistent with preservation of The disclosure under Principal Strategies in the Summary Section of the Prospectus will be deletedand replaced with the following.

7 Under normal circumstances, the Portfolio invests at least 80% of its net assets (plus the amountof borrowings for investment purposes) in government bonds. For purposes of thisdisclosure, government bonds are debt instruments issued or guaranteed by the or its agencies and instrumentalities, including Treasury Inflation Protected Securities(TIPS) and mortgage-backed securities issued or guaranteed by the Government NationalMortgage Association (GNMA or Ginnie Mae), the Federal National Mortgage Association(FNMA or Fannie Mae) or the Federal Home Loan Mortgage Corporation (FHLMC or FreddieMac). Should the Adviser determine that the Portfolio would benefit from reducing the percentageof its net assets invested in government bonds from 80% to a lesser amount, it will notify youat least 60 days prior to the change and will change its name.

8 The Portfolio may invest insovereign debt securities. These securities are issued or guaranteed by foreign Portfolio s portfolio securities may be of any maturity. The Adviser uses fundamental,quantitative and technical investment research techniques to determine what debt obligations tobuy and sell. The total return sought by the Portfolio consists of income earned on thePortfolio s investments plus, if any, capital appreciation. The Portfolio may also invest in Series ofthe Thrivent Core Funds, which are mutual funds that are only offered to the Portfolio and itsaffiliates and that do not charge an investment advisory The following risks will be added under Principal Risks in the Summary Section of the Prospectus :Government Securities Portfolio invests in securities issued or guaranteed by the or its agencies and instrumentalities (such as Ginnie Mae, Fannie Mae or Freddie Macsecurities).

9 Securities issued or guaranteed by Ginnie Mae, Fannie Mae or Freddie Mac are notissued directly by the government. Ginnie Mae is a wholly owned corporation that isauthorized to guarantee, with the full faith and credit of the government, the timely paymentof principal and interest of its securities. By contrast, securities issued or guaranteed by organizations such as Fannie Mae and Freddie Mac are not backed by the fullfaith and credit of the government. No assurance can be given that the governmentwould provide financial support to its agencies and instrumentalities if not required to do so bylaw.

10 In addition, the value of government securities may be affected by changes in the creditrating of the Security debt securities, such as TIPS, are subject to theeffects of changes in market interest rates caused by factors other than inflation (real interestrates). In general, the price of an inflation-linked security tends to decrease when real interest ratesincrease and can increase when real interest rates decrease. Interest payments on inflation-linkedsecurities are unpredictable and will fluctuate as the principal and interest are adjusted forinflation. Any increase in the principal amount of an inflation-linked debt security will beconsidered taxable ordinary income, even though the Portfolio will not receive the principal can also be no assurance that the inflation index used will accurately measure the real rateof inflation in the prices of goods and services.