SPMO tracks the S&P 500 Momentum Index, which selects the S&P 500 stocks with the highest momentum scores, based on price performance over roughly the past year adjusted for volatility, and weights them by momentum score and market capitalization. The index is rebalanced semi-annually, so sector weights can change significantly from one rebalance to the next. Momentum strategies have done well when market leadership is stable and have been prone to sharp reversals when leadership changes.
