After a long period of underperformance, small-cap U.S. stocks may be staging a comeback. While it's too early to say for sure whether this is the start of a sustained rally or just an occasional rise, recent data shows encouraging signs for small-cap investors.The small-cap index iShares Russell 2000 has gained 11% over the past three months (as of Sept. 25, 2025) versus about 7.6% gains in the S&P 500. However, iShares Russell 2000 ETF (IWM) (up 8.2%) still lags SPDR S&P 500 ETF Trust (SPY) (up 12.6%) whe ...