Strategy. MFS (Massachusetts Financial Services Company, the fund's investment adviser) seeks to achieve the funds objective by generating returns from (1) a strategic allocation to three MFS equity funds, referred to as underlying funds, and (2) a tactical asset allocation overlay primarily using derivative instruments to seek to decrease the volatility of the funds returns by reducing the funds exposure to the equity and/or currency markets as represented by the underlying funds and also to potentially expose the fund to asset classes and/or markets in which the underlying funds have little or no exposure (e.g., high income debt instruments). In addition, MFS may use derivatives to seek to limit the funds exposure to certain extreme market events. Derivatives include futures, forward … Show more… MFS (Massachusetts Financial Services Company, the fund's investment adviser) seeks to achieve the funds objective by generating returns from (1) a strategic allocation to three MFS equity funds, referred to as underlying funds, and (2) a tactical asset allocation overlay primarily using derivative instruments to seek to decrease the volatility of the funds returns by reducing the funds exposure to the equity and/or currency markets as represented by the underlying funds and also to potentially expose the fund to asset classes and/or markets in which the underlying funds have little or no exposure (e.g., high income debt instruments). In addition, MFS may use derivatives to seek to limit the funds exposure to certain extreme market events. Derivatives include futures, forward contracts, options, and swaps. It is expected that the fund will generally have lower volatility than that of the overall equity market. The portfolio managers are responsible for selecting the underlying funds, determining the target strategic allocations to the underlying funds, and determining the fund's tactical allocation overlay. Strategic Fund Allocation : The underlying funds are selected by the portfolio managers based on underlying fund classifications, historical risk, performance, and other factors. MFS expects the funds target allocation to be equally weighted among the following underlying funds: MFS Growth Fund, MFS International Equity Fund, and MFS Value Fund. A portion of the fund's assets (approximately 10%-15%) will typically be held in cash, cash equivalents, and/or short-term government securities due to collateral requirements for the fund's investments in derivatives, purchase and redemption activity, and other short term cash needs. Tactical Asset Allocation Overlay : MFS implements the tactical asset allocation overlay primarily through the use of derivative instruments based on the portfolio managers' assessment of the relative attractiveness of asset classes and markets. In seeking to reduce the fund's volatility, MFS decreases the funds exposure to the equity and/or currency markets represented by the underlying funds. In addition, MFS may expose the fund to asset classes and/or markets in which the underlying funds have little or no exposure (e.g., high income debt instruments or small cap equity securities) when the portfolio managers believe such asset classes or markets are relatively attractive. After taking into account the tactical asset allocation overlay, the fund's total market exposure will normally be between 10% and 90% of the fund's assets. (The fund's total market exposure includes the fund's exposure to the equity market through investment in the underlying funds and exposure to any other markets through the tactical overlay.) When the portfolio managers' assessment of the relative attractiveness of asset classes and markets is neutral, the fund's exposure to the equity market is expected to be approximately 50% of the fund's assets. After taking into account the tactical overlay, the fund may have significant exposure to issuers in a single sector, industry, country, or region. MFS' tactical asset allocation process for the fund will typically make extensive use of derivatives. In light of the funds principal investment strategies described above, MFS believes it is reasonable to measure the funds performance (net of fund expenses) over a full market cycle relative to the performance of (i) the ICE BofA 0-3 Month U.S. Treasury Bill Index plus 2% to 4% and (ii) the Standard & Poor's 500 Stock Index. MFS does not seek to achieve a specific rate of return in managing the fund and there is no assurance that the fund will outperform the ICE BofA 0-3 Month U.S. Treasury Bill Index or the Standard & Poor's 500 Stock Index over the long term or for any year or period of years. Show less