BOSTON -- Pay a fund manager above-average fees and it's reasonable to expect you'll have a better than 50-50 chance of beating the stock market.

Yet the latest numbers show a majority of managers aren't keeping up their end of the deal. It's a key reason why investors have been pulling cash out of managed funds at a rapid clip in recent years. It's even happening to big mutual funds that have delivered above-market returns.

A few ugly numbers:

--Over the past five years, nearly 58 percent of managed U.S. stock funds failed to beat a broad measure of the market, the Standard & Poor's Composite 1500. That's according to S&P's ninth annual scorecard of managed fund-vs.-index performance.

--Investors pulled a net $323 billion from managed stock funds over the past four years, according to Morningstar. That's about 10 percent of the assets those funds hold.

Index funds are different animals. Their investors expect to match performance of the market segment the fund tracks. Index funds typically charge less than managed funds, because they don't have to pay investment-picking pros.

It's an approach that continues to gain momentum, 35 years after Vanguard launched the first index fund. Investors have deposited a net

$108 billion into U.S. stock index funds the past four years.

Index funds still trail managed funds. Only $1 of every $4 that individuals invest in U.S. stock funds is in index funds. That suggests most investors continue to believe managers are more likely than not to earn their higher fees.

That puzzles Srikant Dash, a managing director at S&P, who says plenty of managers can beat the market for two or three years. But their numbers drop off sharply over five years.

Dash says that five-year dropoff is the only thing that's consistent from S&P's analysis of more than a decade of fund returns.

In S&P's latest scorecard, managed funds trailed nearly across the board, regardless of the types of stocks they invest in. In 16 of 17 fund categories, average five-year returns trailed those of comparable S&P market indexes. The lone exception: large-cap value funds.

S&P evaluates category returns based on simple averages. Fund manager performance looks better when the returns are asset-weighted, meaning bigger funds count more toward the average than smaller ones. This method aims to reflect where investors put most of their money.

Market-beating returns, however, don't necessarily protect a managed fund from losing investors. Here are examples of stock funds that have had investors withdraw huge sums, despite beating the S&P 500 from 2007 through 2010.

--Fidelity Blue Chip Growth (FBGRX). This nearly $15 billion large-cap growth fund delivered an average annual return of 4.5 percent over that four-year period, versus the S&P 500's average annual loss of 0.8 percent. Yet it suffered nearly $9 billion in net withdrawals over those years, according to Morningstar.

--Putnam Voyager (PVOYX). This $5.2 billion large-cap growth fund has seen $6 billion exit, despite returning an average 7 percent.

--Calamos Growth (CVGRX): More than $8 billion has flowed out of this $9.4 billion large-cap growth fund, despite its 2.9 percent average return.

The second-largest amount withdrawn from a stock fund belongs to one that lost slightly less than the market: American Funds Investment Company of America (AIVSX). Nearly $21 billion was pulled out from the nearly $64 billion large-blend fund. Its four-year average loss was 0.6 percent.

The biggest downsizing was the nearly $25 billion pulled from American Funds Washington Mutual (AWHSX), now a $53 billion fund. It averaged an annual loss of 1.6 percent.

On the other end of the spectrum, the largest amount of new money, unsurprisingly, belongs to an index fund: Vanguard Total Stock Market (VTSMX). Some $56 billion has come in, to boost its asset total to $164 billion. Its four-year return is essentially flat, at 0.02 percent.

Many fund managers argue that their prospects will improve in coming months, and perhaps years. They predict the market will enter a new phase where their stock-picking expertise stands a better chance of making a difference than during the last four years of volatile markets.

That's because managers like Bob Doll expect that the recent gains in the stock market will start to flatten out: "That's when active managers tend to do better."

As the lead manager of a group of large-cap funds run by asset-management giant BlackRock, Doll says that there are still potential breakout stocks that will post above-market returns. Managers can offer their research and analysis to help investors who want to do more than simply go along for the ride, as they would with index funds.

Still, Dash says S&P's findings don't support that. Over the last decade, a majority of fund managers have lagged the market during periods when stocks meandered, as well as during stretches when sharply rose or fell.

"It doesn't matter, if the market is going up, down, or sideways," Dash says.