Rising instability among some of the biggest US stocks is driving a measure of single-stock “fragility” to record levels, with the market increasingly vulnerable to whipsaw patterns among clusters of shares such as occurred in the dot-com bubble of the late 1990s.
Stock fragility, a measure of a company’s daily share-price move relative to its recent volatility, is on track to reach its highest in more than 30 years among the largest 50 stocks in the S&P 500 Index, based on the average magnitude and frequency of such individual shocks so far in 2025, according to Bank of America Corp. strategists.
