Strategy. The Fund operates under a fund of funds structure. The Fund, under normal circumstances, invests substantially all of its assets in iShares exchange-traded funds (Underlying ETFs) or financial instruments that provide exposure to such Underlying ETFs. The Underlying ETFs, in turn, invest in domestic equity securities (stocks) and/or domestic fixed income securities (bonds). The Fund, under normal circumstances, through the Underlying ETFs, invests at least 80% of its assets in a portfolio of investments that provides exposure to U.S. securities. The Underlying ETF strategy is sub-advised by BlackRock Investment Management, LLC (BlackRock). The Underlying ETFs are managed by BlackRock Fund Advisors. The Fund also seeks to stabilize its overall portfolio volatility and reduce downside exposure with a risk management strategy. … Show more… The Fund operates under a fund of funds structure. The Fund, under normal circumstances, invests substantially all of its assets in iShares exchange-traded funds (Underlying ETFs) or financial instruments that provide exposure to such Underlying ETFs. The Underlying ETFs, in turn, invest in domestic equity securities (stocks) and/or domestic fixed income securities (bonds). The Fund, under normal circumstances, through the Underlying ETFs, invests at least 80% of its assets in a portfolio of investments that provides exposure to U.S. securities. The Underlying ETF strategy is sub-advised by BlackRock Investment Management, LLC (BlackRock). The Underlying ETFs are managed by BlackRock Fund Advisors. The Fund also seeks to stabilize its overall portfolio volatility and reduce downside exposure with a risk management strategy. This is a type of risk management sometimes referred to as an overlay because the risk management portion of the portfolio supplements the Funds main investment portfolio. Underlying ETF Allocation Strategy . Under normal circumstances, approximately 70% of the Funds Underlying ETF assets are invested primarily in domestic equity securities (stocks) and approximately 30% of the Funds Underlying ETF assets are invested primarily in domestic fixed income securities (bonds). BlackRock develops the Funds asset allocation strategy based on the Funds investment objective. The Fund allocates a substantial portion of its assets in Underlying Funds employing a passive investment style (i.e., index funds) or a multi-factor style. The Funds largest allocation is to Underlying ETFs that invest primarily in domestic equity securities, including securities of small- and medium-capitalization companies and those with growth and value characteristics. Small-capitalization companies generally include companies with market capitalizations similar to those within the Russell 2000 Index or a similar broad-based index, and medium-capitalization companies generally include companies with market capitalizations similar to those within the Russell MidCap Index or a similar broad-based index. A smaller allocation is made to Underlying ETFs that invest primarily in domestic fixed income securities, including mortgage-backed securities, high yield securities (otherwise known as junk bonds), and securities backed by the U.S. Treasury. The financial instruments that are intended to provide exposure similar to the exposure to the Underlying ETFs may include, among other instruments, futures, options, swaps, structured notes and other derivatives. As a result of the Funds use of futures, options, swaps, structured notes and other derivatives, the Fund may also hold U.S. Treasury, short-term, or other fixed income investments, including loans and notes to address regulatory requirements. On at least an annual basis, BlackRock will reassess and may make revisions in the Funds asset allocation strategy consistent with the Funds investment strategy and objective, including revising the weightings among the investments described above and adding or removing Underlying ETFs from the asset allocation strategy. The Adviser also will periodically rebalance the weightings in the Underlying ETFs to the current asset allocation strategy. In general, the Adviser does not anticipate making frequent changes in the asset allocation strategy and will not attempt to time the market. The Adviser uses various analytical tools and third-party research to construct the portfolio. The Underlying ETF selection is made based on the Funds particular asset allocation strategy, the Advisers desired asset class exposures, and the investment styles and performance of the Underlying ETFs. The Adviser also considers the portfolio characteristics and risk profile for each Underlying ETF over various periods and market environments to assess each Underlying ETFs suitability as an investment for the Fund. The full list of Underlying Funds used by the Fund is included in the Funds annual and semi-annual reports and quarterly holdings disclosures. Risk Management Strategy. Milliman Financial Risk Management LLC (Milliman or overlay manager) implements the Funds risk management strategy. Although up to 20% of the Funds assets may be used to implement the risk management strategy, under normal market conditions, it is expected that less than 10% of the Funds net assets will be used for the strategy. Milliman uses a proprietary volatility forecasting model to manage the assets allocated to this strategy. As part of the risk management strategy, Milliman will invest the portion of Fund assets not invested in Underlying Funds in exchange-traded futures or options contracts, cash collateral to support these contracts and/or high-quality short-term money market investments. Milliman also may use interest rate futures as part of the risk management strategy. The risk management strategy consists of using hedging instruments (short or long positions in exchange-traded futures or options contracts) to stabilize the Funds overall portfolio volatility and reduce the downside exposure of the Fund during significant market downturns. Volatility in this context is a statistical measurement of the frequency and level of changes in the Funds returns without regard to the direction of those changes. Volatility may result from rapid and dramatic price swings of securities held directly or indirectly by the Fund. Parameterization and implementation of the volatility forecasting model may be adjusted based upon changes in market conditions. Milliman uses a proprietary model to monitor and forecast volatility and will adjust the level of exchange-traded futures or options contracts on that basis. Futures or options contracts can be purchased or sold by the Fund for less than their contract value, allowing an efficient use of Fund assets for the risk management strategy. The risk management strategy is separate and distinct from any riders or features of your insurance contract. Milliman selects individual futures or options contracts on indices of domestic and foreign markets that it believes are highly correlated to the Funds investment exposure. Milliman primarily will buy or sell (short) futures or options contracts on these indices to decrease the Funds aggregate economic exposure (from both Underlying Funds and exchange-traded futures or options) based upon Millimans evaluation of market volatility and downside market risk. Short futures contracts increase in value as domestic and/or foreign markets decline. Milliman will seek to hedge currency risks involved in the foreign futures contracts primarily through the use of exchange-traded currency futures contracts. Interest rate futures also may be used in an effort to control the volatility of the Funds returns and to synthetically earn a yield premium on the Funds cash holdings. Even in periods of low volatility in the markets, Milliman will continue to use the hedging techniques designed to preserve gains in favorable market conditions and reduce losses in adverse market conditions. The Funds investment in exchange-traded futures or options and their resulting costs could limit the upside participation of the Fund in strong, appreciating markets relative to unhedged funds. In situations of extreme market volatility, the short positions held in exchange-traded futures or options could potentially reduce the Funds net economic exposure to domestic and foreign securities to a substantial degree. Show less