By Bill Saporito
September 18, 2014

It would be reasonable to assume that the professionals running CalPERS, the California pension fund with $300 billion in assets, would be good at picking stocks. Or at least reasonably good at picking other smart people to pick stocks for them. But in the past year, CalPERS has made two decisions that are telling for all investors when it comes to trying to outperform the market.

Late last year, the pension fund signaled its intention to move more assets from active management into passively managed index funds. These are funds in which you buy a market, such as the S&P 500 or the Russell 2000, unlike mutual funds that try to select winners within a given class of equities. More recently, CalPERS said it would also pull out the $4 billion it has invested in hedge funds. Although hedge-fund honchos make headlines with their personal wealth, the industry has significantly lagged the market in the past three years. “Call it capitulation or sobriety: it’s saying that we can’t beat the market and we can’t find managers who can beat the market, and even if they can, their fee structures are overwhelming,” says Mitch Tuchman, CEO of Rebalance IRA, an investment adviser focused on index-fund-only portfolios.

The CalPERS move is a nod to University of Chicago economist Eugene Fama, who won a Nobel for his lifelong work on “efficient markets.” That theory says that because stock prices reflect all available information at any moment–they are informationally “efficient”–future prices are unpredictable, so trying to beat the market is useless. According to the SPIVA (S&P Indices Versus Active) Scorecard, the return on the S&P 500 beat 87% of active managers in domestic large-cap equity funds over the past five years.

Why can’t expert money managers succeed? Researchers from the University of Chicago say there are so many smart managers that they offset one another, gaining or losing at others’ expense and winding up near the market average, before expenses. “Unless you have some really special information about a manager, there’s really no good reason to put your money in actively managed mutual funds,” says Juhani Linnainmaa, associate professor of finance at Chicago’s Booth School of Business. He says the median managed fund produces an average –1% alpha–that is, below the expected return. Some funds do beat their index–what’s not clear is why. “What is the luck factor?” he asks. “Given the noise in the market, it’s kind of hopeless to try to figure anything out of this.” Linnainmaa’s colleague, finance professor Lubos Pastor, also found that mutual funds have decreasing returns to scale. Size hurts a manager’s ability to trade.

Yet even if managers match the market, they’ve got expense ratios that then eat into returns. Index-fund proponents like John Bogle at Vanguard have long preached that fees dilute performance. A 1% difference can be huge. “It’s not 1% of all your money,” says Tuchman, “it’s 1% of expected returns: that’s 16% to 20%.” The average balance in Fidelity 401(k) plans was $89,300 in 2013. While 1% of that is $893, if you earned 8% compounded over 10 years, your balance would be $192,792; at 7% it’s $175,667, a difference of $17,125. Real money, in other words.

Investors are getting the message, pouring some $345 billion into passive mutual and exchange-traded funds over the past 12 months vs. $126 billion in active funds, says Morningstar. “At the end of the day,” says Tuchman, “an index fund is run by a computer, a robot. We don’t want to believe that a robot can beat Ivy League M.B.A.s–and I’m one of them.” What CalPERS seems to be saying is that the game is over. The robot wins.

Contact us at editors@time.com.

This appears in the September 29, 2014 issue of TIME.

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