USML is engineered to provide twice the daily price fluctuations of the MSCI USA Minimum Volatility Index. This benchmark is derived by refining the broader MSCI USA Index, its primary reference, with the goal of assembling a portfolio that exhibits the lowest possible volatility, all while adhering to specified criteria. The method for achieving this optimization involves an estimated co-variance matrix, which is developed using the Barra multi-factor equity model.