It's been a tough year for running large-cap mutual funds

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All those headlines about new stock market highs may look sexy, but life for active managers hasn't been quite so much fun.

In fact, running large-cap mutual funds has been a rough business, with about 80 percent underperforming the in 2014, according to S&P Capital IQ Fund Research. That's four out of five managers who've failed to match a simple stock market index fund that usually has lower fees and other advantages.

There are a handful of explanations for why performance has been so weak this year, but at the core seems to be the general and stunningly persistent belief that the market remains ahead of itself, with danger always right around the corner. Fear of a looming correction has kept many investors playing defense.

"We've gone 35 months without a decline of 10 percent or more, and the median since World War II is 12 months," said Sam Stovall, S&P's chief equity strategist. "Everybody seems to be waiting for that all-elusive correction, when everyone will pile in. But if everybody's waiting for it, it won't happen."