The Financial Industry Regulatory Authority has warned investors of risks associated with "smart beta" exchange-traded funds. "Because there's no definition of what the heck smart beta even is, it's hard to issue a warning," David Nadig, director of ETFs at FactSet, said. Still, FINRA tried. The self-regulatory organization recommended investors read funds' prospectuses, carefully evaluate the costs and risk, and take note of funds' holdings and liquidity. Read the original story from The WSJ.