IJR tracks the S&P SmallCap 600 index, competing directly with Vanguard's VB. Its top holdings include names like Corcept Therapeutics and Glaukos — names you won't typically see in large-cap ETFs.

Its 22.0% one-year return has recently outpaced VB's 17.4%. Because the two funds track different underlying indexes (S&P 600 vs. the CRSP small-cap index), their holdings differ somewhat, which can produce return gaps like this.