0001065698 2025-12-31 2025-12-31 0001065698 cik0001065698:S000023374Member 2025-12-31 2025-12-31 SUPPLEMENT TO THE PROSPECTUSSupplement dated January 27, 2026, to the Prospectus dated April 30, 2025.MFS® New Discovery Value Portfolio<div style="border-bottom:3pt; border-bottom-style:solid; border-bottom-color:#999999; padding:0pt 0pt 1pt 0pt;"><div style="font-size:5.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal;"></div></div> Effective June 10, 2026, the following is added as the first paragraph in the sub-sections entitled "Principal Investment Strategies" under the main headings entitled "Summary of Key Information" and "Investment Objective, Strategies, and Risks":MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in value companies. Value companies are companies that MFS believes are undervalued compared to their perceived worth in the marketplace. MFS considers a number of factors when determining whether a company is undervalued, including whether (i) the issuer is included in an index which is representative of value companies; (ii) the issuer is classified as a value company by an independent third party financial data provider and/or (iii) the issuer exhibits the characteristics of a value company, considering metrics such as such as price-to-book ratio, price-to-earnings ratio, and dividend yield relative to the applicable equity market. Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures.Effective June 10, 2026, the following sentence in the sub-section entitled "Principal Investment Strategies" under the main heading entitled "Summary of Key Information" is deleted in its entirety:MFS focuses on investing the fund's assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).Effective June 10, 2026, the following sentence is added as the last paragraph in the sub-sections entitled "Principal Investment Strategies" under the main headings entitled "Summary of Key Information" and "Investment Objective, Strategies, and Risks":For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. 2025-04-30 MFS® New Discovery Value Portfolio N-1A 2026-01-27 497 2026-01-27 2025-12-31 0001065698 2026-01-27 false MFS VARIABLE INSURANCE TRUST III