Initial Class Prospectus | MFS Money Market Portfolio | Initial Class

MFS Money Market Portfolio Summary of Key Information

Investment Objective

The fund’s investment objective is to seek current income consistent with preservation of capital and liquidity.

Fees and Expenses

This table describes the fees and expenses that you may pay when you hold shares of the fund.  If the fees and expenses imposed by the insurance company that issued your variable contracts through which the fund is offered were included, your expenses would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Annual Fund Operating Expenses	Initial Class Prospectus MFS Money Market Portfolio Initial Class
Management Fee	0.50%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.05%
Total Annual Fund Operating Expenses	0.55%

Example

This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. If the fees and expenses imposed by the investment vehicle through which an investment in the fund is made were included, your expenses would be higher.

The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Initial Class Prospectus MFS Money Market Portfolio Initial Class	56	176	307	689

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets in U.S. dollar-denominated money market instruments and repurchase agreements. Money market instruments include bank certificates of deposit and other bank obligations of U.S. and foreign banks; notes, commercial paper, and asset-backed securities of U.S. and foreign issuers; U.S. and foreign government securities; and municipal instruments.

MFS will invest at least 25% of the fund’s assets in issuers in the industries in the financial services sector.

In buying and selling investments for the fund, MFS seeks to comply with Securities and Exchange Commission rules for money market funds regarding credit quality, diversification, liquidity, and maturity. MFS stresses maintaining a stable $1.00 share price, liquidity, and income.

Principal Risks

Although the fund seeks to preserve the value of your investment at $1.00 per share, the fund may not achieve its objective and you could lose money on your investment in the fund.  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.

The principal risks of investing in the fund are:

Interest Rate, Credit, and Liquidity Risk: Although MFS seeks to maintain a stable $1.00 share price for the fund, there is no guarantee that it will be able to do so. A major increase in interest rates or a decline in the credit quality of an issuer or entity providing credit support, an inactive trading market for money market instruments, or adverse market, economic, industry, political, regulatory, geopolitical, and other conditions could cause the fund’s share price to decrease to below $1.00.

Foreign Exposure Risk: Exposure to foreign markets can involve increased risks due to adverse market, economic, political, regulatory, geopolitical, and other conditions.

Financial Services Sector Risk:  Events that affect the financial services sector may have a significant adverse effect on the fund.

Municipal Risk: The price of a municipal instrument can be volatile and significantly affected by adverse tax or court rulings, legislative or political changes, changes in specific or general market and economic conditions, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in these industries can significantly affect the fund and the overall municipal market.

Investment Selection Risk:  MFS’ investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability to perform in accordance with the terms of the transaction.

Liquidity Risk: It may not be possible to sell certain investments, types of investments, and/or segments of the market at any particular time or at an acceptable price.

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.

The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the investment vehicle through which an investment in the fund is made were included, they would reduce the returns shown.

Initial Class Bar Chart.

The total return for the three-month period ended March 31, 2013 was 0.00%. During the period(s) shown in the bar chart, the highest quarterly return was 1.22% (for the calendar quarter ended September 30, 2007) and the lowest quarterly return was 0.00% (for the calendar quarter ended March 31, 2009, June 30, 2009, September 30, 2009, December 31, 2009, March 31, 2010, June 30, 2010, September 30, 2010, December 31, 2010, March 31, 2011, June 30, 2011, September 30, 2011, December 31, 2011, March 31, 2012, June 30, 2012, September 30, 2012, and December 31, 2012).

Performance Table.

Average Annual Total Returns (for the Periods Ended December 31, 2012)

Average Annual Returns	Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Initial Class Prospectus MFS Money Market Portfolio Initial Class	Initial Class Shares	none	0.40%	1.55%