Shares of everything from technology giants to household-goods companies and utility providers have been trading in lockstep over the past month, a potentially worrying sign to investors trying to navigate a turbulent market.
The S&P 500’s one-month realized correlation—a measure of how stocks in the benchmark index have moved in relation to one another over the past 30 days—climbed to 65.3% on Sept. 13, according to Susquehanna International Group.
