0001104659-12-086854.txt : 20121231 0001104659-12-086854.hdr.sgml : 20121231 20121231085135 ACCESSION NUMBER: 0001104659-12-086854 CONFORMED SUBMISSION TYPE: 485BPOS PUBLIC DOCUMENT COUNT: 7 FILED AS OF DATE: 20121231 DATE AS OF CHANGE: 20121231 EFFECTIVENESS DATE: 20121231 FILER: COMPANY DATA: COMPANY CONFORMED NAME: MFS VARIABLE INSURANCE TRUST III CENTRAL INDEX KEY: 0001065698 IRS NUMBER: 000000000 FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 485BPOS SEC ACT: 1933 Act SEC FILE NUMBER: 333-59093 FILM NUMBER: 121292493 BUSINESS ADDRESS: STREET 1: 111 HUNTINGTON AVENUE CITY: BOSTON STATE: MA ZIP: 02199 BUSINESS PHONE: 617-954-5000 MAIL ADDRESS: STREET 1: 111 HUNTINGTON AVENUE CITY: BOSTON STATE: MA ZIP: 02199 FORMER COMPANY: FORMER CONFORMED NAME: SUN CAPITAL ADVISERS TRUST DATE OF NAME CHANGE: 19980709 FILER: COMPANY DATA: COMPANY CONFORMED NAME: MFS VARIABLE INSURANCE TRUST III CENTRAL INDEX KEY: 0001065698 IRS NUMBER: 000000000 FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 485BPOS SEC ACT: 1940 Act SEC FILE NUMBER: 811-08879 FILM NUMBER: 121292494 BUSINESS ADDRESS: STREET 1: 111 HUNTINGTON AVENUE CITY: BOSTON STATE: MA ZIP: 02199 BUSINESS PHONE: 617-954-5000 MAIL ADDRESS: STREET 1: 111 HUNTINGTON AVENUE CITY: BOSTON STATE: MA ZIP: 02199 FORMER COMPANY: FORMER CONFORMED NAME: SUN CAPITAL ADVISERS TRUST DATE OF NAME CHANGE: 19980709 0001065698 S000008069 MFS Global Real Estate Portfolio C000021901 Initial Class SCREX C000021902 Service Class SRESX 0001065698 S000008071 MFS Blended Research Small Cap Equity Portfolio C000021905 Initial Class SCOSX C000021906 Service Class SCOMX 0001065698 S000018843 MFS Mid Cap Value Portfolio C000052149 Initial Class shares SCGMX C000052150 Service Class shares SGMCX 0001065698 S000018844 MFS Limited Maturity Portfolio C000052151 Initial Class shares SGSSX C000052152 Service Class shares SGSDX 0001065698 S000023371 MFS Conservative Allocation Portfolio C000068440 Initial Class SCIMX C000068441 Service Class SIMSX 0001065698 S000023372 MFS Moderate Allocation Portfolio C000068442 Initial Class SCIBX C000068443 Service Class SIBSX 0001065698 S000023373 MFS Growth Allocation Portfolio C000068444 Initial Class SIBGX C000068445 Service Class SIGSX 0001065698 S000023374 MFS New Discovery Value Portfolio C000068446 Initial Class SCDSX C000068447 Service Class SDSSX 0001065698 S000023378 MFS Inflation-Adjusted Bond Portfolio C000068454 Initial Class SCBIX C000068455 Service Class SBISX 485BPOS 1 a12-26236_22485bpos.htm POST-EFFECTIVE AMENDMENT FILED PURSUANT TO SECURITIES ACT RULE 485(B)

 

As filed with the Securities and Exchange Commission on December 31, 2012

1933 Act File No. 333-59093

1940 Act File No. 811-08879

 

 

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

 


 

FORM N-1A

 

REGISTRATION STATEMENT

UNDER THE SECURITIES ACT OF 1933

 

POST-EFFECTIVE AMENDMENT NO. 36

 

AND

 

REGISTRATION STATEMENT

UNDER THE INVESTMENT COMPANY ACT OF 1940

 

AMENDMENT NO. 37

 

MFS® VARIABLE INSURANCE TRUST III

(formerly, SUN CAPITAL ADVISERS TRUST®)

(Exact name of registrant as specified in charter)

 

111 Huntington Avenue, Boston, Massachusetts  02199

(Address of principal executive offices)

 

Registrant’s Telephone Number, including Area Code: (617) 954-5000

 

Susan S. Newton, Massachusetts Financial Services Company

111 Huntington Avenue, Boston, Massachusetts  02199

(Name and Address of Agent for Service)

 

APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:

It is proposed that this filing will become effective (check appropriate box)

 

x immediately upon filing pursuant to paragraph (b)

o on [date] pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(i)

o on [date] pursuant to paragraph (a)(i)

o 75 days after filing pursuant to paragraph (a)(ii)

o on [date] pursuant to paragraph (a)(ii) of rule 485

 

If appropriate, check the following box:

o this post-effective amendment designates a new effective date for a previously filed post-effective amendment

 

 

 



 

SIGNATURES

 

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Boston and The Commonwealth of Massachusetts on the 31st day of December, 2012

 

 

 

 

MFS® VARIABLE INSURANCE TRUST III

 

 

(formerly, Sun Capital Advisers Trust®)

 

 

 

 

 

 

 

 

 

 

By:

JOHN M. CORCORAN*

 

 

Name:

John M. Corcoran

 

 

Title:

President

 

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to its Registration Statement has been signed below by the following persons in the capacities indicated on December 31, 2012.

 

SIGNATURE

 

TITLE

 

 

 

 

 

 

JOHN M. CORCORAN*

 

President (Principal Executive Officer)

John M. Corcoran

 

 

 

 

 

 

 

 

DAVID L. DILORENZO*

 

Principal Financial and Accounting Officer

David L. DiLorenzo

 

 

 

 

 

 

 

 

ROBERT E. BUTLER*

 

Trustee

Robert E. Butler

 

 

 

 

 

 

 

 

MAUREEN R. GOLDFARB*

 

Trustee

Maureen R. Goldfarb

 

 

 

 

 

 

 

 

DAVID H. GUNNING*

 

Trustee

David H. Gunning

 

 

 



 

WILLIAM R. GUTOW*

 

Trustee

William R. Gutow

 

 

 

 

 

 

 

 

MICHAEL HEGARTY*

 

Trustee

Michael Hegarty

 

 

 

 

 

 

 

 

JOHN P. KAVANAUGH*

 

Trustee

John P. Kavanaugh

 

 

 

 

 

 

 

 

ROBERT J. MANNING*

 

Trustee

Robert J. Manning

 

 

 

 

 

 

 

 

J. DALE SHERRATT*

 

Trustee

J. Dale Sherratt

 

 

 

 

 

 

 

 

LAURIE J. THOMSEN*

 

Trustee

Laurie J. Thomsen

 

 

 

 

 

 

 

 

ROBERT W. UEK*

 

Trustee

Robert W. Uek

 

 

 

 

 

 

 

*By:

SUSAN S. NEWTON

 

 

Name:  Susan S. Newton

 

 

as Attorney-in-fact

 

 

 

 

 

Executed by Susan S. Newton on behalf of those indicated pursuant to a Power of Attorney, dated December 7, 2012 (Trustees), and a Power of Attorney, dated December 7, 2012 (Corcoran) (DiLorenzo); filed herewith.

 



 

MFS Series Trust I

MFS Series Trust II

MFS Series Trust III

MFS Series Trust IV

MFS Series Trust V

MFS Series Trust VI

MFS Series Trust VII

MFS Series Trust VIII

MFS Series Trust IX

MFS Series Trust X

MFS Series Trust XI

MFS Series Trust XII

MFS Series Trust XIII

MFS Series Trust XIV

MFS Series Trust XV

MFS Series Trust XVI

Massachusetts Investors Growth Stock Fund

Massachusetts Investors Trust

MFS Institutional Trust

MFS Municipal Series Trust

MFS Variable Insurance Trust

MFS Variable Insurance Trust II

MFS Variable Insurance Trust III

MFS California Municipal Fund

MFS Charter Income Trust

MFS Government Markets Income Trust

MFS High Income Municipal Trust

MFS High Yield Municipal Trust

MFS InterMarket Income Trust I

MFS Intermediate High Income Fund

MFS Intermediate Income Trust

MFS Investment Grade Municipal Trust

MFS Multimarket Income Trust

MFS Municipal Income Trust

MFS Special Value Trust

 

(each a “Registrant”)

 

POWER OF ATTORNEY

 

The undersigned, a Trustee of each of the above-mentioned Registrants, hereby severally constitutes and appoints Mark N. Polebaum, Susan S. Newton, Christopher R. Bohane, Thomas H. Connors, Brian E. Langenfeld and Susan A. Pereira, and each of them singly, as true and lawful attorneys, with full power to them and each of them to sign for each of the undersigned, in the names of, and in the

 



 

capacities indicated below, any Registration Statement and any and all amendments thereto and to file the same with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission for the purpose of registering the Registrant as a management investment company under the Investment Company Act of 1940 and/or the shares issued by the Registrant under the Securities Act of 1933 granting unto my said attorneys, and each of them, acting alone, full power and authority to do and perform each and every act and thing requisite or necessary or desirable to be done in the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys or any of them may lawfully do or cause to be done by virtue thereof.

 

IN WITNESS WHEREOF, the undersigned have hereunto set their hand on this 7th day of December, 2012.

 

 

ROBERT E. BUTLER

 

Trustee

Robert E. Butler

 

 

 

 

 

 

 

 

MAUREEN R. GOLDFARB

 

Trustee

Maureen R. Goldfarb

 

 

 

 

 

 

 

 

DAVID H. GUNNING

 

Trustee

David H. Gunning

 

 

 

 

 

 

 

 

WILLIAM R. GUTOW

 

Trustee

William R. Gutow

 

 

 

 

 

 

 

 

MICHAEL HEGARTY

 

Trustee

Michael Hegarty

 

 

 

 

 

 

 

 

JOHN P. KAVANAUGH

 

Trustee

John P. Kavanaugh

 

 

 

 

 

 

 

 

ROBERT J. MANNING

 

Trustee

Robert J. Manning

 

 

 

 

 

 

 

 

J. DALE SHERRATT

 

Trustee

J. Dale Sherratt

 

 

 



 

LAURIE J. THOMSEN

 

Trustee

Laurie J. Thomsen

 

 

 

 

 

 

 

 

ROBERT W. UEK

 

Trustee

Robert W. Uek

 

 

 



 

MFS Series Trust I

MFS Series Trust II

MFS Series Trust III

MFS Series Trust IV

MFS Series Trust V

MFS Series Trust VI

MFS Series Trust VII

MFS Series Trust VIII

MFS Series Trust IX

MFS Series Trust X

MFS Series Trust XI

MFS Series Trust XII

MFS Series Trust XIII

MFS Series Trust XIV

MFS Series Trust XV

MFS Series Trust XVI

Massachusetts Investors Growth Stock Fund

Massachusetts Investors Trust

MFS Institutional Trust

MFS Municipal Series Trust

MFS Variable Insurance Trust

MFS Variable Insurance Trust II

MFS Variable Insurance Trust III

MFS California Municipal Fund

MFS Charter Income Trust

MFS Government Markets Income Trust

MFS High Income Municipal Trust

MFS High Yield Municipal Trust

MFS InterMarket Income Trust I

MFS Intermediate High Income Fund

MFS Intermediate Income Trust

MFS Investment Grade Municipal Trust

MFS Multimarket Income Trust

MFS Municipal Income Trust

MFS Special Value Trust

 

(each a “Registrant”)

 

POWER OF ATTORNEY

 

The undersigned, being the President and Principal Executive Officer, and Treasurer and Principal Financial and Accounting Officer, respectively, of each of the above-mentioned Registrants, hereby severally constitutes and appoints Mark N. Polebaum, Susan S. Newton, Christopher R. Bohane,

 



 

Thomas H. Connors, Brian E. Langenfeld and Susan A. Pereira, and each of them singly, as true and lawful attorneys, with full power to them and each of them to sign for each of the undersigned, in the names of, and in the capacities indicated below, any Registration Statement and any and all amendments thereto and to file the same with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission for the purpose of registering the Registrant as a management investment company under the Investment Company Act of 1940 and/or the shares issued by the Registrant under the Securities Act of 1933 granting unto my said attorneys, and each of them, acting alone, full power and authority to do and perform each and every act and thing requisite or necessary or desirable to be done in the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys or any of them may lawfully do or cause to be done by virtue thereof.

 

IN WITNESS WHEREOF, the undersigned have hereunto set their hand on this 7th day of December, 2012.

 

 

JOHN M. CORCORAN

 

President (Principal Executive Officer)

John M. Corcoran

 

 

 

 

 

 

 

 

DAVID L. DILORENZO

 

Principal Financial and Accounting Officer

David L. DiLorenzo

 

 

 



 

MFS VARIABLE INSURANCE TRUST III

 

MFS® BLENDED RESEARCH SMALL CAP EQUITY PORTFOLIO (formerly, SCSM BlackRock Small Cap Index Fund)

MFS® CONSERVATIVE ALLOCATION PORTFOLIO (formerly, SCSM Ibbotson Conservative Fund)

MFS® GLOBAL REAL ESTATE PORTFOLIO (formerly, Sun Capital Global Real Estate Fund)

MFS® GROWTH ALLOCATION PORTFOLIO (formerly, SCSM Ibbotson Growth Fund)

MFS® INFLATION-ADJUSTED BOND PORTFOLIO (formerly, SCSM BlackRock Inflation Protected Bond Fund)

MFS® LIMITED MATURITY PORTFOLIO (formerly, SCSM Goldman Sachs Short Duration Fund)

MFS® MID CAP VALUE PORTFOLIO (formerly, SCSM Goldman Sachs Mid Cap Value Fund)

MFS® MODERATE ALLOCATION PORTFOLIO (formerly, SCSM Ibbotson Balanced Fund)

MFS® NEW DISCOVERY VALUE PORTFOLIO (formerly, SCSM Columbia Small Cap Value Fund)

 

INDEX TO EXHIBITS

 

EXHIBIT NO.

 

DESCRIPTION OF EXHIBIT

 

PAGE NO.

 

 

 

 

 

101

 

Risk/Return summary of each Fund’s prospectus as an Interactive Data File using eXtensible Business Reporting Language (“XBRL”).

 

 

 


EX-101.INS 2 ck0001065698-20111231.xml XBRL INSTANCE DOCUMENT 485BPOS 2011-12-31 0001065698 2012-12-10 MFS VARIABLE INSURANCE TRUST III false 2012-12-07 2012-12-10 Because MFS may invest a relatively large percentage of the fund's assets in a single issuer or small number of issuers, the fund's performance could be closely tied to the value of that one issuer or issuers, and could be more volatile than the performance of diversified funds. <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance.&#xA0;&#xA0;During the most recent fiscal year, the fund's portfolio<br />turnover rate was 430% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023378Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023378Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return that exceeds the rate of<br />inflation over the long-term, with an emphasis on current income, but also<br />considering capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br />&#xA0;&#xA0;<br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in inflation-adjusted<br />debt instruments and other instruments with similar economic characteristics to<br />these instruments.<br /> <br />MFS currently intends to focus the fund's investments in inflation-adjusted debt<br />instruments issued by the U.S. Treasury. MFS may also invest the fund's assets<br />in other inflation-adjusted debt instruments, other instruments with similar<br />economic characteristics to these instruments, including derivatives, and<br />non-inflation-adjusted debt instruments. <br /> <br />MFS primarily invests the fund's assets in investment grade debt instruments,<br />but may also invest in less than investment grade quality debt instruments<br />(lower quality debt instruments). <br /> <br />MFS may invest the fund's assets in U.S. and foreign securities. <br /> <br />The fund is a non-diversified fund. This means that MFS may invest a relatively<br />large percentage of the fund's assets in a single issuer or a small number of<br />issuers. <br /> <br />While MFS may use derivatives for any investment purpose, to the extent MFS uses<br />derivatives, MFS expects to use derivatives primarily to increase or decrease<br />exposure to a particular market, segment of the market, or security, to increase<br />or decrease interest rate or currency exposure, or as alternatives to direct<br />investments. Derivatives include futures, forward contracts, options, structured<br />securities, inverse floating rate instruments, and swaps. <br /> <br />MFS allocates the fund's assets across maturities and types of debt instruments<br />based on its evaluation of U.S. and foreign macroeconomic factors, including<br />interest rates, inflation rates, and monetary and fiscal policies.<br /> <br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual instruments and their issuers. Quantitative models that systematically <br />evaluate instruments may also be considered. In structuring the fund, MFS may <br />also consider top-down factors.</tt> Summary of Key Information Effective December 8, 2012, the Barclays World Government Inflation-Linked Bond Index replaced the Barclays US Treasury Inflation-Protected Securities Index because MFS believes the Barclays World Government Inflation-Linked Bond Index better reflects the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 4.30 Service Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Barclays World Government Inflation-Linked Bond<br />Index replaced the Barclays US Treasury Inflation-Protected Securities Index<br />because MFS believes the Barclays World Government Inflation-Linked Bond Index<br />better reflects the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012 was 5.41%.<br />During the period(s) shown in the bar chart, the highest quarterly return was<br />3.95% (for the calendar quarter ended September 30, 2011) and the lowest<br />quarterly return was (1.33)% (for the calendar quarter ended December 31, 2010).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /> <br />The principal risks of investing in the fund are: <br /> <br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes. <br /> <br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions. <br /> <br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments. <br /> <br />U.S. Government securities not supported as to the payment of principal or<br />interest by the U.S. Treasury are subject to greater credit risk than are U.S.<br />Government securities supported by the U.S. Treasury. <br /> <br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market. <br /> <br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended. <br /> <br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline. <br /> <br />Non-Diversification Risk: Because MFS may invest a relatively large percentage<br />of the fund's assets in a single issuer or small number of issuers, the fund's<br />performance could be closely tied to the value of that one issuer or issuers,<br />and could be more volatile than the performance of diversified funds. <br /> <br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br />&#xA0;&#xA0;<br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br />&#xA0;&#xA0;<br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests. <br /> <br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction. <br /> <br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance. <br /> <br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023378Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023378Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays US Treasury Inflation-Protected Securities Index 0.1356 0.0833 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays World Government Inflation-Linked Bond Index 0.1065 0.0641 2008-10-01 SBISX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 86 2011-09-30 268 -0.0133 0.0491 1037 466 0.0395 0.1170 0.0009 0.0050 2010-12-31 0.0834 The total return for the nine-month period ended 0.1170 0.0025 0.0084 0.0730 2008-10-01 0.0541 Because MFS may invest a relatively large percentage of the fund's assets in a single issuer or small number of issuers, the fund's performance could be closely tied to the value of that one issuer or issuers, and could be more volatile than the performance of diversified funds. <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 430% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023378Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023378Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return that exceeds the rate of<br />inflation over the long-term, with an emphasis on current income, but also<br />considering capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /> <br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in inflation-adjusted<br />debt instruments and other instruments with similar economic characteristics to<br />these instruments. <br /> <br />MFS currently intends to focus the fund's investments in inflation-adjusted debt<br />instruments issued by the U.S. Treasury. MFS may also invest the fund's assets<br />in other inflation-adjusted debt instruments, other instruments with similar<br />economic characteristics to these instruments, including derivatives, and<br />non-inflation-adjusted debt instruments. <br /> <br />MFS primarily invests the fund's assets in investment grade debt instruments,<br />but may also invest in less than investment grade quality debt instruments<br />(lower quality debt instruments).<br />&#xA0;&#xA0;<br />MFS may invest the fund's assets in U.S. and foreign securities.<br /> <br />The fund is a non-diversified fund. This means that MFS may invest a relatively<br />large percentage of the fund's assets in a single issuer or a small number of<br />issuers. <br /> <br />While MFS may use derivatives for any investment purpose, to the extent MFS uses<br />derivatives, MFS expects to use derivatives primarily to increase or decrease<br />exposure to a particular market, segment of the market, or security, to increase<br />or decrease interest rate or currency exposure, or as alternatives to direct<br />investments. Derivatives include futures, forward contracts, options, structured<br />securities, inverse floating rate instruments, and swaps. <br /> <br />MFS allocates the fund's assets across maturities and types of debt instruments<br />based on its evaluation of U.S. and foreign macroeconomic factors, including<br />interest rates, inflation rates, and monetary and fiscal policies.<br /> <br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual instruments and their issuers. Quantitative models that systematically <br />evaluate instruments may also be considered. In structuring the fund, MFS may also <br />consider top-down factors.</tt> Summary of Key Information Effective December 8, 2012, the Barclays World Government Inflation-Linked Bond Index replaced the Barclays US Treasury Inflation-Protected Securities Index because MFS believes the Barclays World Government Inflation-Linked Bond Index better reflects the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 4.30 Initial Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Barclays World Government Inflation-Linked Bond<br />Index replaced the Barclays US Treasury Inflation-Protected Securities Index<br />because MFS believes the Barclays World Government Inflation-Linked Bond Index<br />better reflects the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012 was 5.64%.<br />During the period(s) shown in the bar chart, the highest quarterly return was<br />3.95% (for the calendar quarter ended September 30, 2011) and the lowest<br />quarterly return was (1.15)% (for the calendar quarter ended December 31, 2010).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency. <br /> <br />The principal risks of investing in the fund are:<br /> <br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /> <br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions. <br /> <br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /> <br />U.S. Government securities not supported as to the payment of principal or<br />interest by the U.S. Treasury are subject to greater credit risk than are U.S.<br />Government securities supported by the U.S. Treasury. <br /> <br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market. <br /> <br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /> <br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline. <br /> <br />Non-Diversification Risk: Because MFS may invest a relatively large percentage<br />of the fund's assets in a single issuer or small number of issuers, the fund's<br />performance could be closely tied to the value of that one issuer or issuers,<br />and could be more volatile than the performance of diversified funds. <br /> <br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br />&#xA0;&#xA0;<br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br />&#xA0;&#xA0;<br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /> <br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction. <br /> <br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance. <br /> <br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023378Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023378Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays US Treasury Inflation-Protected Securities Index 0.1356 0.0833 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays World Government Inflation-Linked Bond Index 0.1065 0.0641 2008-10-01 SCBIX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 60 2011-09-30 189 -0.0115 0.0524 738 329 0.0395 0.1190 0.0009 0.0050 2010-12-31 0.0872 The total return for the nine-month period ended 0.1190 0.00 0.0059 0.0759 2008-10-01 0.0564 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance.&#xA0;&#xA0;During the most recent fiscal year, the fund's portfolio<br />turnover rate was 50% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023374Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023374Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br />&#xA0;&#xA0;<br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests the fund's assets primarily in equity securities. Equity<br />securities include common stocks, preferred stocks, securities convertible into<br />stocks, and depositary receipts for such securities. <br /> <br />MFS focuses on investing the fund's assets in the stocks of companies it<br />believes are undervalued compared to their perceived worth (value companies). <br /> <br />While MFS may invest the fund's assets in companies of any size, MFS generally<br />focuses on companies with small capitalizations. <br /> <br />MFS may invest the fund's assets in foreign securities.<br /> <br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual issuers. Quantitative models that systematically evaluate issuers may<br />also be considered.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.50 Service Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012 was 7.23%.<br />During the period(s) shown in the bar chart, the highest quarterly return was<br />22.29% (for the calendar quarter ended June 30, 2009) and the lowest quarterly<br />return was (21.52)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency. <br /> <br />The principal risks of investing in the fund are:<br />&#xA0;&#xA0;<br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general. <br /> <br />Value Company Risk: The stocks of value companies can continue to be<br />undervalued for long periods of time and not realize their expected value and<br />can be more volatile than the market in general.<br />&#xA0;&#xA0;<br />Small Cap Risk: The stocks of small cap companies can be more volatile than<br />stocks of larger companies.<br />&#xA0;&#xA0;<br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /> <br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests. <br /> <br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance. <br /> <br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements<br />with MFS. If the fees and expenses imposed by the insurance company that issued<br />your variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023374Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023374Member2 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell 2000 Value Index -0.0550 0.0196 2008-10-01 SDSSX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 132 2009-06-30 422 -0.2152 -0.0010 0.2133 1661 745 0.2229 -0.0650 0.0025 0.0090 2014-12-31 2011-09-30 0.3007 The total return for the nine-month period ended -0.0650 0.0025 0.0130 0.0140 0.0516 2008-10-01 0.0723 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 50% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023374Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023374Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /> <br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests the fund's assets primarily in equity securities. Equity<br />securities include common stocks, preferred stocks, securities convertible into<br />stocks, and depositary receipts for such securities. <br /> <br />MFS focuses on investing the fund's assets in the stocks of companies it<br />believes are undervalued compared to their perceived worth (value companies). <br /><br />While MFS may invest the fund's assets in companies of any size, MFS generally<br />focuses on companies with small capitalizations. <br /> <br />MFS may invest the fund's assets in foreign securities. <br /> <br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual issuers. Quantitative models that systematically evaluate issuers may<br />also be considered.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.50 Initial Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012 was 7.42%.<br />During the period(s) shown in the bar chart, the highest quarterly return was<br />22.44% (for the calendar quarter ended June 30, 2009) and the lowest quarterly<br />return was (21.49)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br />&#xA0;&#xA0;<br />The principal risks of investing in the fund are: <br /> <br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /> <br />Value Company Risk: The stocks of value companies can continue to be undervalued<br />for long periods of time and not realize their expected value and can be more<br />volatile than the market in general. <br /> <br />Small Cap Risk: The stocks of small cap companies can be more volatile than<br />stocks of larger companies.<br />&#xA0;&#xA0;<br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market. <br /> <br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br />&#xA0;&#xA0;<br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance.<br />&#xA0;&#xA0;<br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements<br />with MFS. If the fees and expenses imposed by the insurance company that issued<br />your variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023374Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023374Member1 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell 2000 Value Index -0.0550 0.0196 2008-10-01 SCDSX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 107 2009-06-30 344 -0.2149 -0.0010 0.2162 1378 612 0.2244 -0.0632 0.0025 0.0090 2014-12-31 2011-09-30 0.3052 The total return for the nine-month period ended -0.0632 0.00 0.0105 0.0115 0.0543 2008-10-01 0.0742 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 16% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023373Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023373Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a greater than moderate level of risk relative to the other MFS<br />Asset Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are<br />MFS Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and<br />MFS Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /> <br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>The fund is designed to provide diversification among different asset classes <br />by investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure. <br /> <br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was: <br /> <br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;21%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;20%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;54%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;11%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;11%</tt> Summary of Key Information Effective December 8, 2012, the Standard & Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended Index replaced the Dow Jones Moderately Aggressive U.S. Relative Risk Portfolio Index because MFS believes the Standard & Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.16 Service Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Standard &amp; Poor's 500 Stock Index and the <br />MFS Growth Allocation Fund Blended Index replaced the Dow Jones Moderately<br />Aggressive U.S. Relative Risk Portfolio Index because MFS believes the<br />Standard &amp; Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended<br />Index better reflect the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was<br />10.59%.&#xA0;&#xA0;During the period(s) shown in the bar chart, the highest quarterly<br />return was 16.75% (for the calendar quarter ended June 30, 2009) and the lowest<br />quarterly return was (14.69)% (for the calendar quarter ended September 30,<br />2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /> <br />The principal risks of investing in the fund are: <br /> <br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests. <br /> <br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective. <br /> <br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general. <br /> <br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems, <br />and greater political, social, and economic instability than developed markets. <br /> <br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br />&#xA0;&#xA0;<br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general. <br /> <br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general. <br /> <br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes. <br /> <br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions. <br /> <br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments. <br /> <br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /> <br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline. <br /> <br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market. <br /> <br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors. The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources.<br /> <br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage. <br /> <br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br />&#xA0;&#xA0;<br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction. <br /> <br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance. <br /> <br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023373Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023373Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) MFS Growth Allocation Fund Blended Index -0.0024 0.0479 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Dow Jones Moderately Aggressive U.S. Relative Risk Portfolio Index 0.0145 0.0704 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Standard & Poor's 500 Stock Index 0.0211 0.0465 2008-10-01 SIGSX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 121 2009-06-30 378 -0.1469 0.1361 1443 654 0.1675 -0.0390 0.0006 0.0000 2011-09-30 0.2675 The total return for the nine-month period ended -0.0390 0.0025 0.0119 0.0651 2008-10-01 0.1059 0.0088 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 16% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023373Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023373Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a greater than moderate level of risk relative to the other MFS<br />Asset Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are<br />MFS Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and<br />MFS Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /> <br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>The fund is designed to provide diversification among different asset classes <br />by investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /> <br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was: <br /> <br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;21%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;20%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;54%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;11%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;11%</tt> Summary of Key Information Effective December 8, 2012, the Standard & Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended Index replaced the Dow Jones Moderately Aggressive U.S. Relative Risk Portfolio Index because MFS believes the Standard & Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.16 Initial Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Standard &amp; Poor's 500 Stock Index and the <br />MFS Growth Allocation Fund Blended Index replaced the Dow Jones Moderately<br />Aggressive U.S. Relative Risk Portfolio Index because MFS believes the<br />Standard &amp; Poor's 500 Stock Index and the MFS Growth Allocation Fund Blended<br />Index better reflect the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was<br />10.87%.&#xA0;&#xA0;During the period(s) shown in the bar chart, the highest quarterly<br />return was 16.85% (for the calendar quarter ended June 30, 2009) and the lowest<br />quarterly return was (14.70)% (for the calendar quarter ended September 30,<br />2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency. <br /> <br />The principal risks of investing in the fund are: <br /> <br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests. <br /> <br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective. <br /> <br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /> <br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems, <br />and greater political, social, and economic instability than developed markets.&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;<br /> <br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /> <br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general.<br /> <br />Value Company Risk: The stocks of value companies can continue to be<br />undervalued for long periods of time and not realize their expected value <br />and can be more volatile than the market in general.<br />&#xA0;&#xA0;<br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes. <br /> <br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions. <br /> <br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />nstruments.<br /> <br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /> <br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline. <br /> <br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /> <br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors. The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources. <br /> <br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br /> <br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /> <br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction. <br /> <br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance. <br /> <br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023373Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023373Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) MFS Growth Allocation Fund Blended Index -0.0024 0.0479 2008-10-01 Index Comparisons (Reflects no deduction for fees, Dow Jones Moderately Aggressive U.S. Relative Risk Portfolio Index 0.0145 0.0704 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Standard & Poor's 500 Stock Index 0.0211 0.0465 2008-10-01 SIBGX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 96 2009-06-30 300 -0.1470 0.1380 1155 520 0.1685 -0.0366 0.0006 0.0000 2011-09-30 0.2717 The total return for the nine-month period ended -0.0366 0.00 0.0094 0.0675 2008-10-01 0.1087 0.0088 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 7% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023372Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023372Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a moderate level of risk relative to the other MFS Asset<br />Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS<br />Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS<br />Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>The fund is designed to provide diversification among different asset classes <br />by investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was:<br /><br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;41%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;12%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;13%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;43%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1.5%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1.5%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%</tt> Summary of Key Information Effective December 8, 2012, the Standard & Poor's 500 Stock Index and the MFS Moderate Allocation Fund Blended Index replaced the Dow Jones Moderate U.S. Relative Risk Portfolio Index because MFS believes the Standard & Poor's 500 Stock Index and the MFS Moderate Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.07 Service Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Standard &amp; Poor's 500 Stock Index and the MFS<br />Moderate Allocation Fund Blended Index replaced the Dow Jones Moderate U.S.<br />Relative Risk Portfolio Index because MFS believes the Standard &amp; Poor's 500<br />Stock Index and the MFS Moderate Allocation Fund Blended Index better reflect<br />the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 9.13%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />13.43% (for the calendar quarter ended June 30, 2009) and the lowest quarterly<br />return was (11.20)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective.<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems, <br />and greater political, social, and economic instability than developed markets.<br /><br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general.<br /><br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general.<br /><br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline.<br /><br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors.&#xA0;&#xA0;The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources.<br /><br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.&#xA0;&#xA0;Derivatives can involve leverage.<br /><br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023372Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023372Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) MFS Moderate Allocation Fund Blended Index 0.0222 0.0577 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Dow Jones Moderate U.S. Relative Risk Portfolio Index 0.0332 0.0754 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Standard & Poor's 500 Stock Index 0.0211 0.0465 2008-10-01 SIBSX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 112 2009-06-30 350 -0.1120 0.1182 1340 606 0.1343 -0.0181 0.0004 0.0000 2011-09-30 0.2365 The total return for the nine-month period ended -0.0181 0.0025 0.0110 0.0658 2008-10-01 0.0913 0.0081 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 7% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023372Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023372Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a moderate level of risk relative to the other MFS Asset<br />Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS<br />Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS<br />Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>The fund is designed to provide diversification among different asset classes by<br />investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was:<br /><br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;41%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;12%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;13%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;3%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;43%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;7%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1.5%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1.5%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;9%</tt> Summary of Key Information Effective December 8, 2012, the Standard & Poor's 500 Stock Index and the MFS Moderate Allocation Fund Blended Index replaced the Dow Jones Moderate U.S. Relative Risk Portfolio Index because MFS believes the Standard & Poor's 500 Stock Index and the MFS Moderate Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.07 Initial Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Standard &amp; Poor's 500 Stock Index and the MFS<br />Moderate Allocation Fund Blended Index replaced the Dow Jones Moderate U.S.<br />Relative Risk Portfolio Index because MFS believes the Standard &amp; Poor's 500<br />Stock Index and the MFS Moderate Allocation Fund Blended Index better reflect<br />the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 9.30%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />13.40% (for the calendar quarter ended June 30, 2009) and the lowest quarterly<br />return was (11.11)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective.<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems, <br />and greater political, social, and economic instability than developed markets.<br /><br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general.<br /><br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general.<br /><br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors. The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources.<br /><br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br /><br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies.&#xA0;&#xA0;The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023372Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023372Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) MFS Moderate Allocation Fund Blended Index 0.0222 0.0577 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Dow Jones Moderate U.S. Relative Risk Portfolio Index 0.0332 0.0754 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Standard & Poor's 500 Stock Index 0.0211 0.0465 2008-10-01 SCIBX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 87 2009-06-30 271 -0.1111 0.1218 1049 471 0.1340 -0.0156 0.0004 0.0000 2011-09-30 0.2391 The total return for the nine-month period ended -0.0156 0.00 0.0085 0.0687 2008-10-01 0.0930 0.0081 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 7% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023371Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023371Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a conservative level of risk relative to the other MFS Asset<br />Allocation Portfolios.&#xA0;&#xA0;(The MFS Asset Allocation Portfolios currently are MFS<br />Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS<br />Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>The fund is designed to provide diversification among different asset classes <br />by investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was:<br /><br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;62%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;10%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;12%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;17%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;28%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%</tt> Summary of Key Information Effective December 8, 2012, the Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund Blended Index replaced the Dow Jones Moderately Conservative U.S. Relative Risk Portfolio Index because MFS believes the Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.07 Service Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Barclays U.S. Aggregate Bond Index and the MFS<br />Conservative Allocation Fund Blended Index replaced the Dow Jones Moderately<br />Conservative U.S. Relative Risk Portfolio Index because MFS believes the<br />Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund<br />Blended Index better reflect the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 7.89%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />9.51% (for the calendar quarter ended September 30, 2009) and the lowest<br />quarterly return was (7.38)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective.<br /><br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about the <br />issuer, or the market or economy in general, than higher quality debt instruments.<br /><br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems,<br />and greater political, social, and economic instability than developed markets.<br /><br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline.<br /><br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors. The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources.<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general.<br /><br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general.<br /><br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br /><br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023371Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023371Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees expenses or taxes) MFS Conservative Allocation Fund Blended Index 0.0458 0.0652 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Dow Jones Moderately Conservative U.S. Relative Risk Portfolio Index 0.0507 0.0776 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays U.S. Aggregate Bond Index 0.0784 0.0768 2008-10-01 SIMSX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 106 2009-09-30 331 -0.0738 0.0964 1271 574 0.0951 0.0063 0.0005 0.0000 2011-09-30 0.1922 The total return for the nine-month period ended 0.0063 0.0025 0.0104 0.0597 2008-10-01 0.0789 0.0074 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 7% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000023371Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000023371Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The investment objective of the fund is to seek a high level of total return<br />consistent with a conservative level of risk relative to the other MFS Asset<br />Allocation Portfolios. (The MFS Asset Allocation Portfolios currently are MFS<br />Conservative Allocation Portfolio, MFS Moderate Allocation Portfolio, and MFS<br />Growth Allocation Portfolio.)</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br />&#xA0;&#xA0;<br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees expenses or taxes <tt>The fund is designed to provide diversification among different asset classes <br />by investing its assets in other mutual funds advised by MFS (Massachusetts<br />Financial Services Company, the fund's investment adviser), referred to as<br />underlying funds. The underlying funds are selected following a two stage asset<br />allocation process. The first stage is a strategic asset allocation to determine<br />the percentage of the fund's assets to be invested in the general asset classes<br />of Bond Funds, International Stock Funds, and U.S. Stock Funds, as well as an<br />allocation to underlying funds that have less traditional investment strategies<br />that MFS believes provide diversification benefits when added to a portfolio<br />consisting of stock and bond funds (referred to as Specialty Funds) based on the<br />risk/return potential of the different asset classes and the risk profile of the<br />fund. The second stage involves the actual selection of underlying funds to<br />represent the asset classes based on underlying fund classifications, historical<br />risk, performance, and other factors. Within the stock fund allocations, MFS<br />seeks to diversify globally (by including domestic and international underlying<br />funds), in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds), and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br />&#xA0;&#xA0;<br />As of December 10, 2012, the fund's target allocation among asset classes and<br />the underlying funds was:<br />&#xA0;&#xA0;<br />Bond Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;62%<br />MFS Global Governments Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Government Securities Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;10%<br />MFS High Yield Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;5%<br />MFS Inflation-Adjusted Bond Portfolio&#xA0;&#xA0;&#xA0;10%<br />MFS Limited Maturity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;12%<br />MFS Research Bond Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;17%<br />Specialty Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Global Real Estate Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />International Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;8%<br />MFS Emerging Markets Equity Portfolio&#xA0;&#xA0;&#xA0;&#xA0;0%<br />MFS International Growth Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS International Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;2%<br />MFS Research International Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />U.S. Stock Funds:&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;28%<br />MFS Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%<br />MFS Mid Cap Growth Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS Mid Cap Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;4%<br />MFS New Discovery Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS New Discovery Value Portfolio&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;1%<br />MFS Research Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%<br />MFS Value Series&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;&#xA0;6%</tt> Summary of Key Information Effective December 8, 2012, the Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund Blended Index replaced the Dow Jones Moderately Conservative U.S. Relative Risk Portfolio Index because MFS believes the Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund Blended Index better reflect the fund's current investment strategies. Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.07 Initial Class Bar Chart. Performance Information <tt>Effective December 8, 2012, the Barclays U.S. Aggregate Bond Index and the MFS<br />Conservative Allocation Fund Blended Index replaced the Dow Jones Moderately<br />Conservative U.S. Relative Risk Portfolio Index because MFS believes the<br />Barclays U.S. Aggregate Bond Index and the MFS Conservative Allocation Fund<br />Blended Index better reflect the fund's current investment strategies.</tt> The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 8.07%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />9.66% (for the calendar quarter ended September 30, 2009) and the lowest<br />quarterly return was (7.39)% (for the calendar quarter ended September 30,<br />2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br />&#xA0;&#xA0;<br />The principal risks of investing in the fund are:<br /> <br />Investment Selection and Allocation Risk: MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /> <br />Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategies and may not achieve its objective.<br />&#xA0;&#xA0;<br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br />&#xA0;&#xA0;<br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br />&#xA0;&#xA0;<br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /> <br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems,<br />and greater political, social, and economic instability than developed markets.<br />&#xA0;&#xA0;<br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br />&#xA0;&#xA0;<br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br />&#xA0;&#xA0;<br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline.<br /> <br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br />&#xA0;&#xA0;<br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates and property tax rates; shifts in zoning laws, environmental<br />regulations and other governmental action; cash flow dependency; increased<br />operating expenses; lack of availability of mortgage funds; losses due to<br />natural disasters; overbuilding; losses due to casualty or condemnation; changes<br />in property values and rental rates; and other factors. The securities of<br />smaller real estate-related issuers can be more volatile and less liquid than<br />securities of larger issuers and their issuers can have more limited financial<br />resources.<br />&#xA0;&#xA0;<br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br />&#xA0;&#xA0;<br />Growth Company Risk: The stocks of growth companies can be more sensitive to<br />the company's earnings and more volatile than the market in general.<br />&#xA0;&#xA0;<br />Value Company Risk: The stocks of value companies can continue to be<br />undervalued for long periods of time and not realize their expected value <br />and can be more volatile than the market in general.<br />&#xA0;&#xA0;<br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br />&#xA0;&#xA0;<br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br />&#xA0;&#xA0;<br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br />&#xA0;&#xA0;<br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance.<br />&#xA0;&#xA0;<br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and different investment strategies. The<br />fund's past performance does not necessarily indicate how the fund will perform<br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000023371Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000023371Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparisons (Reflects no deduction for fees, expenses or taxes) MFS Conservative Allocation Fund Blended Index 0.0458 0.0652 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Dow Jones Moderately Conservative U.S. Relative Risk Portfolio Index 0.0507 0.0776 2008-10-01 Index Comparisons (Reflects no deduction for fees, expenses or taxes) Barclays U.S. Aggregate Bond Index 0.0784 0.0768 2008-10-01 SCIMX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 81 2009-09-30 252 -0.0739 0.0992 978 439 0.0966 0.0097 0.0005 0.0000 2011-09-30 0.1937 The total return for the nine-month period ended 0.0097 0.00 0.0079 0.0624 2008-10-01 0.0807 0.0074 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 154% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000018844Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000018844Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return with an emphasis on<br />current income, but also considering capital preservation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests the fund's assets primarily in debt instruments.<br /><br />Debt instruments include corporate bonds, U.S. Government securities,<br />asset-backed securities, municipal instruments, foreign government securities,<br />inflation-adjusted bonds, and other obligations to repay money borrowed.<br /><br />The fund's dollar-weighted average effective maturity will normally not exceed<br />five years.<br /><br />MFS generally invests substantially all of the fund's assets in investment grade<br />debt instruments.<br /><br />MFS invests the fund's assets in U.S. securities and U.S. dollar-denominated<br />foreign securities.<br /><br />While MFS may use derivatives for any investment purpose, to the extent MFS uses<br />derivatives, MFS expects to use derivatives primarily to increase or decrease<br />exposure to a particular market, segment of the market, or security, to increase<br />or decrease interest rate exposure, or as alternatives to direct investments.<br />Derivatives include futures, forward contracts, options, structured securities,<br />inverse floating rate instruments, and swaps.<br /><br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual instruments and their issuers. Quantitative models that systematically <br />evaluate instruments may also be considered. In structuring the fund, MFS may <br />also consider top-down factors.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 1.54 Service Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 2.21%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />1.49% (for the calendar quarter ended September 30, 2009) and the lowest<br />quarterly return was (0.42)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.&#xA0;&#xA0;Derivatives can involve leverage.<br /><br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.<br /><br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance. <br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's past <br />performance does not necessarily indicate how the fund will perform in the future. <br />Updated performance is available at mfs.com or by calling 1-877-411-3325. If the <br />fees and expenses imposed by the investment vehicle through which an investment in <br />the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000018844Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000018844Member2 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays 1-3 Year U.S. Government/Credit Bond Index 0.0159 0.0273 2008-03-07 SGSDX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 74 2009-09-30 230 -0.0042 0.0216 894 401 0.0149 0.0017 0.0007 0.0040 2011-09-30 0.0352 The total return for the nine-month period ended 0.0017 0.0025 0.0072 0.0231 2008-03-07 0.0221 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 154% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000018844Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000018844Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return with an emphasis <br />on current income, but also considering capital preservation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests the fund's assets primarily in debt instruments.<br /><br />Debt instruments include corporate bonds, U.S. Government securities,<br />asset-backed securities, municipal instruments, foreign government securities,<br />inflation-adjusted bonds, and other obligations to repay money borrowed.<br /><br />The fund's dollar-weighted average effective maturity will normally not exceed<br />five years.<br /><br />MFS generally invests substantially all of the fund's assets in investment grade<br />debt instruments.<br /><br />MFS invests the fund's assets in U.S. securities and U.S. dollar-denominated<br />foreign securities.<br /><br />While MFS may use derivatives for any investment purpose, to the extent MFS uses<br />derivatives, MFS expects to use derivatives primarily to increase or decrease<br />exposure to a particular market, segment of the market, or security, to increase<br />or decrease interest rate exposure, or as alternatives to direct investments.<br />Derivatives include futures, forward contracts, options, structured securities,<br />inverse floating rate instruments, and swaps.<br /><br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual instruments and their issuers. Quantitative models that systematically <br />evaluate instruments may also be considered. In structuring the fund, MFS may <br />also consider top-down factors.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 1.54 Initial Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 2.40%. <br />During the period(s) shown in the bar chart, the highest quarterly return was<br />1.55% (for the calendar quarter ended September 30, 2009) and the lowest<br />quarterly return was (0.32)% (for the calendar quarter ended December 31, 2010).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Interest Rate Risk: The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk: The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Prepayment/Extension Risk: Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk: Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline.<br /><br />Municipal Risk: The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Derivatives Risk: Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost. Derivatives can involve leverage.<br /><br />Leveraging Risk: Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.<br /><br />Counterparty and Third Party Risk: Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000018844Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000018844Member1 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays 1-3 Year U.S. Government/Credit Bond Index 0.0159 0.0273 2008-03-07 SGSSX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 48 2009-09-30 151 -0.0032 0.0241 591 263 0.0155 0.0053 0.0007 0.0040 2010-12-31 0.0378 The total return for the nine-month period ended 0.0053 0.00 0.0047 0.0259 2008-03-07 0.0240 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 50% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000018843Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000018843Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in issuers with medium<br />market capitalizations. MFS generally defines medium market capitalization<br />issuers as issuers with market capitalizations similar to those of issuers<br />included in the Russell Midcap Value Index over the last 13 months at the time<br />of purchase. As of October 31, 2012, the range of the Russell Midcap Value Index<br />was between $26.1 million and $18.7 billion.<br /><br />MFS normally invests the fund's assets primarily in equity securities. Equity<br />securities include common stocks, preferred stocks, securities convertible into<br />stocks, and depositary receipts for such securities.<br /><br />MFS focuses on investing the fund's assets in the stocks of companies it<br />believes are undervalued compared to their perceived worth (value companies).<br /><br />MFS may invest the fund's assets in foreign securities.<br /><br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual issuers. Quantitative models that systematically evaluate issuers may<br />also be considered.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.50 Service Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 13.62%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />22.50% (for the calendar quarter ended September 30, 2009) and the lowest <br />quarterly return was (17.29)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline significantly <br />in response to issuer, market, economic, industry, political, regulatory, geopolitical, <br />and other conditions, as well as to investor perceptions of these conditions. The <br />price of an equity security can decrease significantly in response to these conditions, <br />and these conditions can affect a single issuer or type of security, issuers within a <br />broad market sector, industry or geographic region, or the market in general.<br /><br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general.<br /><br />Mid Cap Risk: The stocks of mid cap companies can be more volatile than stocks<br />of larger companies.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's past <br />performance does not necessarily indicate how the fund will perform in the future. <br />Updated performance is available at mfs.com or by calling 1-877-411-3325. If the <br />fees and expenses imposed by the investment vehicle through which an investment in <br />the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000018843Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000018843Member2 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell Midcap Value Index -0.0138 0.0325 2008-03-07 SGMCX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 110 2009-09-30 343 -0.1729 0.2162 1317 595 0.2250 0.0234 0.0008 0.0075 2011-09-30 0.2538 The total return for the nine-month period ended 0.0234 0.0025 0.0108 0.0226 2008-03-07 0.1362 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 50% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000018843Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000018843Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in issuers with medium<br />market capitalizations. MFS generally defines medium market capitalization<br />issuers as issuers with market capitalizations similar to those of issuers<br />included in the Russell Midcap Value Index over the last 13 months at the time<br />of purchase. As of October 31, 2012, the range of the Russell Midcap Value Index<br />was between $26.1 million and $18.7 billion.<br /><br />MFS normally invests the fund's assets primarily in equity securities. Equity<br />securities include common stocks, preferred stocks, securities convertible into<br />stocks, and depositary receipts for such securities. <br /><br />MFS focuses on investing the fund's assets in the stocks of companies it<br />believes are undervalued compared to their perceived worth (value companies).<br /><br />MFS may invest the fund's assets in foreign securities.<br /><br />MFS uses a bottom-up investment approach to buying and selling investments for<br />the fund. Investments are selected primarily based on fundamental analysis of<br />individual issuers. Quantitative models that systematically evaluate issuers may<br />also be considered.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.50 Initial Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 13.85%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />22.59% (for the calendar quarter ended September 30, 2009) and the lowest <br />quarterly return was (17.30)% (for the calendar quarter ended September 30, 2011).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Value Company Risk: The stocks of value companies can continue to be undervalued <br />for long periods of time and not realize their expected value and can be more <br />volatile than the market in general.<br /><br />Mid Cap Risk: The stocks of mid cap companies can be more volatile than stocks<br />of larger companies.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and different investment strategies. The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000018843Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000018843Member1 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell Midcap Value Index -0.0138 0.0325 2008-03-07 SCGMX lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 85 2009-09-30 265 -0.1730 0.2213 1025 460 0.2259 0.0247 0.0008 0.0075 2011-09-30 0.2568 The total return for the nine-month period ended 0.0247 0.00 0.0083 0.0253 2008-03-07 0.1385 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 37% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000008071Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000008071Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in equity securities of<br />issuers with small market capitalizations. MFS generally defines small market<br />capitalization issuers as issuers with market capitalizations similar to those<br />of issuers included in the Russell 2000 Index over the last 13 months at the<br />time of purchase. As of October 31, 2012, the range of the Russell 2000 Index<br />was between $10.4 million and $4.1 billion.<br /><br />Equity securities include common stocks, preferred stocks, securities convertible <br />into stocks, and depositary receipts for such securities.<br /><br />In selecting investments for the fund, MFS is not constrained to any particular<br />investment style. MFS may invest the fund's assets in the stocks of companies it<br />believes to have above average earnings growth potential compared to other<br />companies (growth companies), in the stocks of companies it believes are<br />undervalued compared to their perceived worth (value companies), or in a<br />combination of growth and value companies.<br /><br />MFS may invest the fund's assets in foreign securities.<br /><br />MFS uses a bottom-up approach to buying and selling investments for the fund.<br />Investments are selected based on fundamental analysis of individual issuers and<br />quantitative models that systematically evaluate issuers.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.37 Service Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 13.54%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />31.20% (for the calendar quarter ended June 30, 2009) and the lowest quarterly <br />return was (26.91)% (for the calendar quarter ended December 31, 2008).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Small Cap Risk: The stocks of small cap companies can be more volatile than<br />stocks of larger companies.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Investment Selection Risk: MFS' investment analysis, its development and use of<br />quantitative models, and its selection of investments may not produce the<br />intended results and/or can lead to an investment focus that results in the fund<br />underperforming other funds with similar investment strategies and/or<br />underperforming the markets in which the fund invests.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some<br />indication of the risks of investing in the fund by showing changes in the<br />fund's performance over time and how the fund's performance over time compares<br />with that of a broad measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another<br />adviser or subadviser was responsible for selecting investments for the fund<br />under a different investment objective and using a passive investment strategy.<br />The fund's past performance does not necessarily indicate how the fund will<br />perform in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle<br />through which an investment in the fund is made were included, they would reduce<br />the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000008071Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000008071Member2 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell 2000 Index -0.0418 0.0015 0.0562 SCOMX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 78 2009-06-30 243 -0.2691 0.2407 942 422 -0.0211 0.3120 -0.0509 0.0011 -0.3814 0.0040 2008-12-31 0.3650 -0.0054 The total return for the nine-month period ended -0.0509 0.0025 0.0425 0.0076 0.1354 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 37% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000008071Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000008071Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek capital appreciation.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in equity securities of<br />issuers with small market capitalizations. MFS generally defines small market<br />capitalization issuers as issuers with market capitalizations similar to those<br />of issuers included in the Russell 2000 Index over the last 13 months at the<br />time of purchase. As of October 31, 2012, the range of the Russell 2000 Index<br />was between $10.4 million and $4.1 billion.<br /><br />Equity securities include common stocks, preferred stocks, securities convertible <br />into stocks, and depositary receipts for such securities.<br /><br />In selecting investments for the fund, MFS is not constrained to any particular<br />investment style. MFS may invest the fund's assets in the stocks of companies <br />it believes to have above average earnings growth potential compared to other<br />companies (growth companies), in the stocks of companies it believes are<br />undervalued compared to their perceived worth (value companies), or in a<br />combination of growth and value companies.<br /><br />MFS may invest the fund's assets in foreign securities.<br /><br />MFS uses a bottom-up approach to buying and selling investments for the fund.<br />Investments are selected based on fundamental analysis of individual issuers and<br />quantitative models that systematically evaluate issuers.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.37 Initial Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 13.81%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />31.28% (for the calendar quarter ended June 30, 2009) and the lowest quarterly <br />return was (26.91)% (for the calendar quarter ended December 31, 2008).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect <br />a single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Small Cap Risk: The stocks of small cap companies can be more volatile than<br />stocks of larger companies.<br /><br />Foreign Risk: Exposure to foreign markets through issuers or currencies can<br />involve additional risks relating to market, economic, political, regulatory,<br />geopolitical, or other conditions. These factors can make foreign investments,<br />especially those in emerging markets, more volatile and less liquid than U.S.<br />investments. In addition, foreign markets can react differently to these<br />conditions than the U.S. market.<br /><br />Investment Selection Risk: MFS' investment analysis, its development and use of<br />quantitative models, and its selection of investments may not produce the intended <br />results and/or can lead to an investment focus that results in the fund<br />underperforming other funds with similar investment strategies and/or<br />underperforming the markets in which the fund invests. <br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br /><br />Performance prior to December 8, 2012, reflects time periods when another adviser <br />or subadviser was responsible for selecting investments for the fund under a <br />different investment objective and using a passive investment strategy. The fund's <br />past performance does not necessarily indicate how the fund will perform in the <br />future. Updated performance is available at mfs.com or by calling 1-877-411-3325. <br />If the fees and expenses imposed by the investment vehicle through which an <br />investment in the fund is made were included, they would reduce the returns shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your<br />expenses would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000008071Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000008071Member1 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) Russell 2000 Index -0.0418 0.0015 0.0562 SCOSX -0.2061 lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 52 2009-06-30 164 -0.2691 0.1843 0.2446 640 285 -0.0144 0.3128 -0.0487 0.0011 -0.3799 0.0040 2008-12-31 0.3677 -0.0021 0.0433 The total return for the nine-month period ended -0.0487 0.4162 0.00 0.0456 0.0051 0.1360 0.1381 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 27% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000008069Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000008069Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in U.S. and foreign real<br />estate-related investments.<br /><br />MFS normally invests the fund's assets primarily in equity securities.<br /><br />MFS generally focuses the fund's investments in equity real estate investment<br />trusts ("REITs") as well as similar entities formed under the laws of non-U.S.<br />countries, but may also invest in mortgage REITs, hybrid REITs and other U.S.<br />and foreign real estate-related investments, including emerging market real<br />estate-related investments.<br /><br />MFS may invest the fund's assets in real estate-related investments of any<br />size.&#xA0;&#xA0;However, issuers of real estate-related investments tend to be<br />small-to-medium-sized.<br /><br />MFS typically allocates the fund's investments across various geographic areas,<br />REIT managers and property types, but may from time to time focus the fund's<br />investments in any one or a few of these areas.<br /><br />MFS may invest a large percentage of the fund's assets in issuers in a single<br />country, a small number of countries, or a particular geographic region.<br /><br />MFS selects investments by analyzing the fundamental and relative values of<br />potential investments.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.27 Service Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 20.93%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />34.75% (for the calendar quarter ended June 30, 2009) and the lowest quarterly <br />return was (39.09)% (for the calendar quarter ended December 31, 2008).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Real Estate-Related Investment Risk: The fund's performance will be closely<br />tied to the performance of real estate-related investments and as a result, can<br />be more volatile than the performance of more broadly-diversified funds. The<br />risks of investing in real estate-related investments include certain risks<br />associated with the direct ownership of real estate and the real estate industry<br />in general. These include risks related to general, regional and local economic<br />conditions; fluctuations in interest rates and property tax rates; shifts in<br />zoning laws, environmental regulations and other governmental action; cash flow<br />dependency; increased operating expenses; lack of availability of mortgage<br />funds; losses due to natural disasters; overbuilding; losses due to casualty or<br />condemnation; changes in property values and rental rates; and other factors.<br /><br />Small to Medium Cap Risk: The securities of smaller real estate-related issuers<br />can be more volatile and less liquid than securities of larger issuers and their<br />issuers can have more limited financial resources.<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems,<br />and greater political, social, and economic instability than developed markets.<br /><br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Geographic Concentration Risk: The fund's performance could be closely tied to<br />the market, currency, economic, political, regulatory, geopolitical, or other<br />conditions in the countries or regions in which the fund invests and could be<br />more volatile than the performance of more geographically-diversified funds.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund's net assets in U.S. and foreign real estate-related investments. <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br />&#xA0;&#xA0;<br />The fund's past performance does not necessarily indicate how the fund will perform <br />in the future. Updated performance is available at mfs.com or by calling<br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle through <br />which an investment in the fund is made were included, they would reduce the returns <br />shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000008069Member2 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000008069Member2 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) FTSE EPRA/NAREIT Developed Real Estate Index -0.0582 -0.0528 0.0950 SRESX lowest quarterly return highest quarterly return 2012-09-30 Service Class Shares 122 2009-06-30 386 -0.3909 -0.0005 0.1494 1502 676 -0.1334 0.3475 -0.0774 0.0010 -0.4489 0.0090 2014-12-31 2008-12-31 0.2983 -0.0804 0.0937 The total return for the nine-month period ended -0.0774 0.0025 0.0644 0.0120 0.0125 0.3864 0.2093 <tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs. These transaction costs, which are not<br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the<br />fund's performance. During the most recent fiscal year, the fund's portfolio<br />turnover rate was 27% of the average value of its portfolio.</tt> <div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000008069Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/BarChartData_S000008069Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <tt>The fund's investment objective is to seek total return.</tt> <tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds. If the fees and expenses<br />imposed by the investment vehicle through which an investment in the fund is<br />made were included, your expenses would be higher. <br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods; your<br />investment has a 5% return each year; and the fund's operating expenses remain<br />the same.</tt> Performance Table. Reflects no deduction for fees, expenses or taxes <tt>MFS (Massachusetts Financial Services Company, the fund's investment adviser)<br />normally invests at least 80% of the fund's net assets in U.S. and foreign <br />real estate-related investments. <br /><br />MFS normally invests the fund's assets primarily in equity securities.<br /><br />MFS generally focuses the fund's investments in equity real estate investment<br />trusts ("REITs") as well as similar entities formed under the laws of non-U.S.<br />countries, but may also invest in mortgage REITs, hybrid REITs and other U.S.<br />and foreign real estate-related investments, including emerging market real<br />estate-related investments.<br /><br />MFS may invest the fund's assets in real estate-related investments of any<br />size.&#xA0;&#xA0;However, issuers of real estate-related investments tend to be<br />small-to-medium-sized.<br /><br />MFS typically allocates the fund's investments across various geographic areas,<br />REIT managers and property types, but may from time to time focus the fund's<br />investments in any one or a few of these areas.<br /><br />MFS may invest a large percentage of the fund's assets in issuers in a single<br />country, a small number of countries, or a particular geographic region.<br /><br />MFS selects investments by analyzing the fundamental and relative values of<br />potential investments.</tt> Summary of Key Information Example Investment Objective The fund's past performance does not necessarily indicate how the fund will perform in the future. As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. Principal Risks Although your actual costs will likely be higher or lower, under these assumptions your costs would be: 0.27 Initial Class Bar Chart. Performance Information The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund's performance over time and how the fund's performance over time compares with that of a broad measure of market performance. <tt>The total return for the nine-month period ended September 30, 2012, was 21.23%. <br />During the period(s) shown in the bar chart, the highest quarterly return was <br />34.82% (for the calendar quarter ended June 30, 2009) and the lowest quarterly <br />return was (39.05)% (for the calendar quarter ended December 31, 2008).</tt> 1-877-411-3325 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): Average Annual Total Returns (for the Periods Ended December 31, 2011) Portfolio Turnover <tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund. An investment in the fund is not a<br />bank deposit and is not insured or guaranteed by the Federal Deposit Insurance<br />Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Real Estate-Related Investment Risk: The fund's performance will be closely<br />tied to the performance of real estate-related investments and as a result, can<br />be more volatile than the performance of more broadly-diversified funds. The<br />risks of investing in real estate-related investments include certain risks<br />associated with the direct ownership of real estate and the real estate industry<br />in general. These include risks related to general, regional and local economic<br />conditions; fluctuations in interest rates and property tax rates; shifts in<br />zoning laws, environmental regulations and other governmental action; cash flow<br />dependency; increased operating expenses; lack of availability of mortgage funds; <br />losses due to natural disasters; overbuilding; losses due to casualty or<br />condemnation; changes in property values and rental rates; and other factors.<br /><br />Small to Medium Cap Risk: The securities of smaller real estate-related issuers<br />can be more volatile and less liquid than securities of larger issuers and their<br />issuers can have more limited financial resources.<br /><br />Stock Market/Company Risk: Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Foreign and Emerging Markets Risk: Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, less developed legal, regulatory, and accounting systems,<br />and greater political, social, and economic instability than developed markets.<br /><br />Currency Risk: The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Geographic Concentration Risk: The fund's performance could be closely tied to<br />the market, currency, economic, political, regulatory, geopolitical, or other<br />conditions in the countries or regions in which the fund invests and could be<br />more volatile than the performance of more geographically-diversified funds.<br /><br />Investment Selection Risk: MFS' investment analysis and its selection of<br />investments may not produce the intended results and/or can lead to an<br />investment focus that results in the fund underperforming other funds with<br />similar investment strategies and/or underperforming the markets in which the<br />fund invests.<br /><br />Liquidity Risk: It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt> Fees and Expenses Principal Investment Strategies mfs.com MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund's net assets in U.S. and foreign real estate-related investments. <tt>The bar chart and performance table below are intended to provide some indication <br />of the risks of investing in the fund by showing changes in the fund's performance <br />over time and how the fund's performance over time compares with that of a broad <br />measure of market performance.<br />&#xA0;&#xA0;<br />The fund's past performance does not necessarily indicate how the fund will <br />perform in the future. Updated performance is available at mfs.com or by calling <br />1-877-411-3325. If the fees and expenses imposed by the investment vehicle through <br />which an investment in the fund is made were included, they would reduce the returns <br />shown.</tt> <tt>This table describes the fees and expenses that you may pay when you hold shares<br />of the fund. Expenses have been adjusted to reflect current fee arrangements and<br />the management fee set forth in the fund's Investment Advisory Agreement with<br />MFS. If the fees and expenses imposed by the insurance company that issued your<br />variable contracts through which the fund is offered were included, your expenses <br />would be higher.</tt> <div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000008069Member1 column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> <div style="display:none">~ http://www.mfs.com/role/PerformanceTableData_S000008069Member1 column dei_LegalEntityAxis compact * column rr_PerformanceMeasureAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Index Comparison (Reflects no deduction for fees, expenses or taxes) FTSE EPRA/NAREIT Developed Real Estate Index -0.0582 -0.0528 0.0950 SCREX 0.0404 lowest quarterly return highest quarterly return 2012-09-30 Initial Class Shares 97 2009-06-30 308 -0.3905 0.3332 -0.0005 0.1528 1215 542 -0.1313 0.3482 -0.0759 0.0010 -0.4473 0.0090 2014-12-31 2008-12-31 0.3009 -0.0782 0.0967 The total return for the nine-month period ended -0.0759 0.3595 0.00 0.0670 0.0095 0.0100 0.3896 0.2123 0001065698 ck0001065698:SummaryS000008069-1Memberck0001065698:S000008069Memberck0001065698:C000021901Member 2012-12-10 2012-12-10 0001065698 ck0001065698:SummaryS000008069-1Memberck0001065698:S000008069Memberck0001065698:RRINDEX00001Member 2012-12-10 2012-12-10 0001065698 ck0001065698:SummaryS000008069-1Memberck0001065698:S000008069Member 2012-12-10 2012-12-10 0001065698 ck0001065698:SummaryS000008069-2Memberck0001065698:S000008069Memberck0001065698:C000021902Member 2012-12-10 2012-12-10 0001065698 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2012-12-10 pure iso4217:USD Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 0.95% of the fund's average daily net assets annually for Initial Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2014. Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 1.20% of the fund's average daily net assets annually for Service Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2014. As of December 31, 2011, the MFS Conservative Allocation Fund Blended Index (the "Blended Index") consisted of the following indices and weightings: (28%) Standard & Poor's 500 Stock Index; (8%) MSCI EAFE (Europe, Australasia, Far East) Index; (1%) The Dow Jones-UBS Commodity Index; (1%) FTSE EPRA/NAREIT Developed Real Estate Index; and (62%) Barclays U.S. Aggregate Bond Index. The underlying indices and weightings of the Blended Index may have differed during the period, and may differ in the future. As of December 31, 2011, the MFS Moderate Allocation Fund Blended Index (the "Blended Index") consisted of the following indices and weightings: (41%) Standard & Poor's 500 Stock Index; (13%) MSCI EAFE (Europe, Australasia, Far East) Index; (3%) The Dow Jones-UBS Commodity Index; (2%) FTSE EPRA/NAREIT Developed Real Estate Index; and (41%) Barclays U.S. Aggregate Bond Index. The underlying indices and weightings of the Blended Index may have differed during the period, and may differ in the future. As of December 31, 2011, the MFS Growth Allocation Fund Blended Index (the "Blended Index") consisted of the following indices and weightings: (52%) Standard & Poor's 500 Stock Index; (20%) MSCI EAFE (Europe, Australasia, Far East) Index; (4%); The Dow Jones-UBS Commodity Index; (3%) FTSE EPRA/NAREIT Developed Real Estate Index; and (21%) Barclays U.S. Aggregate Bond Index. The underlying indices and weightings of the Blended Index may have differed during the period, and may differ in the future. Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 1.05% of the fund's average daily net assets annually for Initial Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2014. Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 1.30% of the fund's average daily net assets annually for Service Class shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2014. 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