MarketWatch.com January 4, 2013, 1:00 PM ET

Could your retirement plan be cheaper?

More mutual-fund investors seem to be deciding that “active management” isn’t worth the price. The latest evidence appears in today’s Wall Street Journal, where Kirsten Grind reports that in the first 11 months of 2012, investors pulled $119 billion out of U.S. actively managed stock mutual funds—the most since the 2008 crash—while moving $30 billion into U.S. stock exchange-traded funds. Deeper in the article, Grind cites further signs of a migration: American Funds and Fidelity Investments, two fund giants that rely heavily on actively managed funds, saw net outflows and “weak investor interest,” respectively, in 2012, while the index- and ETF-focused Vanguard Investments recorded $141 billion in net inflows in 2012.

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It warms a jaded personal-finance journalist’s heart to see more investors recognizing the corrosive effects that management fees can have on their savings. Over a working lifetime, paying annual fees of 0.25% or less for an index fund or ETF, rather than 1% or more for active management, can add tens or hundreds of thousands of dollars to someone’s nest egg.

It’s worth keeping in mind, however, that investors whose savings are concentrated in 401(k) plans don’t always have the resources to get the lowest possible costs. Critics have lambasted the retirement-plan industry for years for stocking their plans with higher-cost funds, as MarketWatch’s Ian Salisbury has been diligently reporting. And on the bright side, there’s growing evidence that administrators of such plans have begun to respond to the public disgruntlement by relying more heavily on index funds. (See, for example, Brightscope’s recent report on the nation’s best retirement plans.)

But the even cheaper ETFs remain difficult to find in 401(k)s. Retirement plan giants Fidelity and Charles Schwab have delayed their efforts to make ETFs more widely available in the plans they administer, citing technical challenges related to trading and record-keeping. The financial advisor trade journal RIABiz reported in October that ETF assets make up only about $5 billion of the $3.5 trillion currently held in 401(k)s.

Investors in traditional and Roth IRAs don’t have this problem, of course: Generally, they can invest in whatever they like. And even investors who are bound to a 401(k) may still be able to chase down cheaper funds. About 40% of 401(k) plans have brokerage windows, through which plan members can invest in a much wider range of funds or other assets. (One caveat for

anyone choosing that escape hatch: Remember that making purchases through a brokerage window can incur transaction fees.)