On Friday March 15, the S&P 500 completed its quarterly rebalancing for the first time in 2019.
A little reminder: the S&P 500 is a market-cap weighted index and rebalances four times each year.
Each time, index funds and ETFs that track it have to adjust to follow suit.
Over the past decade, the best-performing S&P industry group in the month after a March S&P quarterly rebalance has been Retail.
It trades higher 80% of the time with an average gain of more than 3%, according to a CNBC analysis using Kensho.
The major industry group laggard has been Banks.