0000918571 2012-11-01 2012-11-01 0000918571 ck0000918571:P0002-S000002675Member ck0000918571:S000002675Member 2012-11-01 2012-11-01 0000918571 ck0000918571:P0001-S000002675Member ck0000918571:S000002675Member 2012-11-01 2012-11-01 Other 2012-11-01 MFS VARIABLE INSURANCE TRUST 0000918571 false 2012-11-01 2012-11-01 2012-04-29 MFS® High Income Series <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">SUPPLEMENT TO PROSPECTUS <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">The date of this supplement is November 1, 2012. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS® High Income Series – Initial <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">Class and Service Class <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">Effective immediately, the sub-section entitled “Principal Investment Strategies” beneath the main heading “Summary of Key Information” is restated in its entirety as follows:   Principal Investment Strategies   <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests directly and/or indirectly through investment in mutual funds advised by MFS at least 80% of the fund’s net assets in high income debt instruments. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest the fund’s assets in other types of debt instruments. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">Debt instruments include corporate bonds, foreign government securities, asset-backed securities, and other obligations to repay money borrowed. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest up to 100% of the fund’s assets directly or indirectly in less than investment grade quality debt instruments (lower quality debt instruments). <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest the fund’s assets in foreign securities. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.   MFS® High Income Series <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">SUPPLEMENT TO PROSPECTUS <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">The date of this supplement is November 1, 2012. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS® High Income Series – Initial <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">Class and Service Class <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">  Effective immediately, the sub-section entitled “Principal Investment Strategies” beneath the main heading “Summary of Key Information” is restated in its entirety as follows: Principal Investment Strategies <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests directly and/or indirectly through investment in mutual funds advised by MFS at least 80% of the fund’s net assets in high income debt instruments. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest the fund’s assets in other types of debt instruments. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">Debt instruments include corporate bonds, foreign government securities, asset-backed securities, and other obligations to repay money borrowed. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest up to 100% of the fund’s assets directly or indirectly in less than investment grade quality debt instruments (lower quality debt instruments). <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">MFS may invest the fund’s assets in foreign securities. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;line-height: normal;text-autospace:none">While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps. <p class="MsoNormal" style="margin-top:0in;margin-right:0in;margin-left:0in;font-size:11.0pt;font-family:'calibri','sans-serif';margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;text-autospace:none">  MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.