(Bloomberg Business) — They're cheap, easy to use, and they're winning over more investors than ever.

Now exchange-traded funds — investment tools that seek to replicate the performance of a portfolio of securities — are growing at such a clip that their assets are poised to overtake those of hedge funds.

It's no secret hedge funds have had a rough couple of years. Without the returns to make up for high taxes and fees, more investors are turning to the ever-growing range of ETF products on offer. ETFs have lower fees than mutual funds, lower taxes than index funds and are easier to buy or sell quickly than either. And underpinning gains is loose central-bank policy that has been fueling a general movement toward passive investing.