Activist hedge funds, which often push for companies to make changes like spin off divisions, buy back shares, or change management, are doing three times as well as the market in general. The activist funds on average were up nearly 6.8% this year, through the end of July, according to new figures from Hedge Fund Research. That is far better than the market. The Standard & Poor’s 500 index was up 2.2% through July. Include dividends and the gain from investing in the S&P 500 is 3.4% this year.

Activist hedge funds have been hot for a few years, gathering more investors. But the returns haven’t always lived up to their hype. Last year, for instance, the average activist fund was up by just 5%, versus 12% for the S&P 500. Activist hedge funds have only beaten the S&P 500 in three of the past eight years.

Among activist investors, Bill Ackman appears to be having a better than average year, with his Pershing Square fund up a little over 10% in the first half of the year. Shares of Ackman’s largest position, drug company Valeant (VRX), are up 73% this year. Food and beverage conglomerate Mondelez (MDLZ), which Ackman recently announced he had taken a $5.5 billion stake in, is also up 18% in the past three months. Ackman says he thinks the snack company needs to cut costs or be sold, and he has floated Heinz Kraft as a potential acquirer. But on Monday, Warren Buffett, whose Berkshire Hathaway along with Brazilian investment firm 3G owns Heinz Kraft, said the food giant wasn’t interested in Mondelez. Shares of Herbalife (HLF) have rebounded, too, this year, hurting Ackman’s performance. Ackman has famously bet against the nutritional supplement company.

H Partners, a relatively small activist fund , appears to be having a good year as well. Earlier this year, H Partners’ Rehan Jaffer, a former deputy of Third Point’s Dan Loeb, forced mattress company Tempur Sealy to revamp its management. Shares of Tempur, one of H Partners’ largest holdings, are up nearly 40% this year.

Last week, Carl Icahn disclosed that his hedge fund was up 8.6% in the first half of the year. Shares of Icahn’s publicly traded company, Icahn Enterprise (IEP), are down 17% this year, largely on account of the firm’s investments in the oil sector. Icahn’s former deputy Keith Meister, who now runs the hedge fund Corvex, appears to be having a good year as well, helped by a rebound in the shares of oil and gas company Williams Companies, the fund’s top holding.

It’s not exactly clear why activist hedge funds would be doing so much better than the market this year. On Monday, the Wall Street Journal reported that it seems like more and more large institutional investors are siding with activist hedge funds in proxy votes. If mutual funds think activists know what they are doing, they may be more predisposed to buy stocks that activists also own, or buy more shares when an activist shows up. That would drive up the performance of the stocks that activists own, and also hurt the performance of others stocks by comparison. Also, if activists are buying first and other investors second, that would lead to more gains for the activists and less for everyone else.

This year’s mergers and acquisitions activity may have also helped activists. We have a seen an uptick in deals, and the market has been generally receptive to the news, with shares of companies involved perking up. Since activists are often involved in companies that do deals, pushing for companies to sell or split up, that’s probably helping their performance as well.

And as more investors put more of their money in index funds, it might be easier for active funds, those that go against the grain, to do better. Although, Fortune has argued in the past that the fact that large index funds are getting more involved in corporate governance issues and board fights may already be making activist investors less relevant.

Or it could just be the luck of the draw. Maybe activists are having a rare good year, making them look smarter than they actually are. Markets do that some time.