One of the more striking developments in investment products in the past decade has been an explosion in the use of ETFs—exchange-traded funds.
According to Morningstar, assets in ETFs have grown to more than $2.1 trillion. About 1,400 different ETFs now exist.
Some ETFs are similar to generic index mutual funds, as they are passively managed. They track an index, like the S&P 500, to capture the returns of that index, minus expenses and trading costs. Like some no-load index funds, these ETFs can have expenses that are quite low.