Rebound tide raised fewer ships than it sank

U.S. equities together fell more during winter's market downturn than they rose in the post-March 23 rebound. Though the term rebound may sound generous, given that the S&P 500 and Russell 1000 are each still down 7.1% this year as of Wednesday afternoon, the indexes bounced back to the tune of 34.15% and 35.4%, respectively, during the past 65 days.

The recovery period, however, wasn't as equal in the rise as it was in the fall. The Cboe S&P 500 Implied Correlation index, which measures how much the underlying 500 or so equities that make up the index change, has come off earlier highs.

Moving out to a larger sample size shows a tighter distribution among year-to-date returns of the Russell 1000 constituents in the period ended March 23 compared to the weeks that followed. The standard deviation of the later period was about 1.7 times that of the earlier period, or 31.4% compared to 18.6%.

The worst performing sectors over the first quarter were some of the best in the subsequent period as well. The technology industry was the only group able to pull its average sector return out of the red.