After climbing more than 20% in 2023, the S&P 500 registered its strongest first-quarter gain of 10.2% in five years. The broader index posted a series of record highs without a noteworthy pullback so far this year. However, momentum stocks have outshined the S&P 500 in the first three months by the biggest margin since 2008. In the first quarter of 2024, the iShares MSCI USA Momentum Factor ETF (MTUM) soared more than 19%, making some investors anxious. This is because, traditionally, outperformance by mom ...