ETFs Target Retirement Market

Exchange-traded funds are starting to make inroads into 401(k) plans, creating the potential for explosive growth in these baskets of securities that trade throughout the day like stocks. But some people are skeptical that ETFs will -- or should -- ever play as big a role as mutual funds in helping Americans plan for retirement.

The market for ETFs rose to $432 billion at the end of 2006 from $464 million in 1993, the year they were launched, according to fund tracker Morningstar. But the industry is still tiny compared with the $10 trillion in mutual funds.

That could change over the coming years as more defined contribution plans offer ETFs as investment options alongside mutual funds and individual stocks. ...