Launches of actively managed exchange-traded vehicles are surging, but their performance is often poor

For most investors, exchange-traded funds are synonymous with passive investment. The asset-management industry is trying to change that—and likely not for the better.

ETFs are the big market story of the past few years: Over the past decade, assets managed by these vehicles in the U.S. have leapt from roughly $1.5 trillion to more than $10 trillion, according to Wall Street a