Strategy. Under normal market conditions, the Portfolio seeks to achieve its investment objective primarily through investing at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in a diversified group of underlying exchange-traded funds ("Underlying ETFs") that are affiliated with the Portfolio's sub-adviser, BlackRock Investment Management, LLC ("BlackRock" or the "Sub-Adviser"). Under normal market conditions, the Sub-Adviser allocates approximately 40% to 80% of the Portfolio's assets to Underlying ETFs that invest primarily in equity securities of both U.S. and non-U.S. issuers and 20% to 60% of the Portfolio's assets to Underlying ETFs that invest primarily in fixed-income securities and/or cash alternatives in both U.S. and non-U.S. markets. The Portfolio incorporates a global tactical asset allocation … Show more… Under normal market conditions, the Portfolio seeks to achieve its investment objective primarily through investing at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in a diversified group of underlying exchange-traded funds ("Underlying ETFs") that are affiliated with the Portfolio's sub-adviser, BlackRock Investment Management, LLC ("BlackRock" or the "Sub-Adviser"). Under normal market conditions, the Sub-Adviser allocates approximately 40% to 80% of the Portfolio's assets to Underlying ETFs that invest primarily in equity securities of both U.S. and non-U.S. issuers and 20% to 60% of the Portfolio's assets to Underlying ETFs that invest primarily in fixed-income securities and/or cash alternatives in both U.S. and non-U.S. markets. The Portfolio incorporates a global tactical asset allocation strategy that, under normal circumstances, seeks to adjust allocations to asset classes that BlackRock deems to be attractive investments over the short to intermediate term. This strategy seeks to enhance the total return and manages portfolio risk at the aggregate level. Modifications in the allocations to the ETFs are based on techniques that may include technical, qualitative, quantitative and momentum analysis of the market. The mix of ETFs will vary with market conditions and BlackRock's assessment of the ETFs' relative attractiveness as investment opportunities. Certain ETFs' investments will focus on investments in securities listed on domestic and foreign equity exchanges with growth and value styles, including, small-, mid- and large-cap issuers, and on investments in domestic and foreign fixed-income instruments including U.S. treasuries, mortgage- and asset-backed securities, corporate loans, distressed securities, inflation-indexed instruments, corporate bonds, sovereign and emerging market debt. An ETF may invest a large percentage of its assets in indices located in a single country, a small number of countries, or a particular geographic region. In addition, the Underlying ETFs may invest in lower quality debt securities. Such securities are sometimes referred to as "junk bonds." An Underlying ETF may integrate environmental, social and governance ("ESG") factors into its investment selection process and/or screen out particular companies and industries based on certain ESG related criteria. An Underlying ETF may also seek to deliver exposure to certain style factors (i.e. quality, value, momentum, size, minimum volatility). The Portfolio may also invest in securities and derivative contracts, including indexes, swap agreements, futures, options, currency forwards, and U.S. Treasury securities, and cash equivalents including, without limitation, commercial paper, and time deposits, as determined by the Sub-Adviser. Show less