A stock market correlation index hit a nearly four-month high on Wednesday, signaling that investors expect stocks to swing higher in the coming days. The S&P 500 fell 0.58% on Wednesday, down nearly 5% from its record high in late March, while the Cboe 1-month implied correlation index rose as high as 21.79, the highest since late December. The Cboe Index, which measures the market's expectations for correlations among S&P 500 components, had recently hovered below 10 points in early April, a low rarely touched in the index's nearly 20-year history, according to LSEG.
Read MoreEquity Correlations Rise as Wall Street Decline Widens