Passive investing in index funds has gained a lot of steam in recent years. But top-performing fund manager David Winters says index-fund investing can actually be dangerous.

In a new report, Winters’ Wintergreen Advisers notes that “Trillions of ordinary investors’ dollars are now committed to a mechanistic strategy that day in and day out simply buys stocks without a thought for their actual underlying value. Students of market history know that index mania — like other market fads before it – will end badly.”

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Wintergreen says index investing powers Vanguard, BlackRock and State Street are “the largest block of shareholders in America’s largest publicly traded companies, holding an average of 16% of the shares outstanding of the top 25 companies in the S&P 500.” And, Winters says, these firms too often vote for executive pay packages that are problematic. “The sad reality is that index funds have turned ordinary investors into the pawns in a game that undermines the integrity of American markets and imposes costs on society that don’t show up in index fund expense ratios,” he says. “We believe that one consequence of this is that billions of dollars of value created by American companies are being diverted to a select few executives while ordinary investors, distracted by ‘low fee’ hype, are subjected to dangerous risk concentrations in their retirement portfolios.”

Wintergreen says that it analyzed the voting histories of the leading S&P 500 index funds run by Vanguard, BlackRock and State Street over the past five years for the 25 largest S&P companies. It says the funds voted for equity compensation plans 89% of the time, and opposed executives’ pay packages less than 4% of the time.