Small caps are outperforming the broader stock market

While still trailing the S&P 500 and other major U.S. stock indexes by a solid margin year to date, the Russell 2000 index, which consists of many of the country's smallest public companies, has outpaced the broader market's rebound since March 23.

The state of play: The Russell 2000 rose 3.1% on Wednesday for its second straight day of gains over 3%. The increase in small cap stocks shows investors growing bullish on the overall U.S. economy.