Hedge funds seem to have a permanent place at the top of the business news. Among the most recent stunners, Blackstone Group announced a billion investment by the Chinese government, capping an earlier announcement that the firm would go public. And a recent survey found that top hedge fund managers make more than billion a year. Despite the industry’s high profile, the 8,800 funds’ inner workings remain shrouded. These lightly regulated investment pools for wealthy investors don’t report their holdings and say little about their investment strategies. With an estimated $1.2 trillion under management, hedge funds must impact the financial markets. The question is: How? In one of the first studies to shed light on that question, researchers at Wharton and three other business schools find that hedge funds’ efforts to improve companies they hold big stakes in have spillover benefits for all shareholders: a quick 5% to 7% jump in stock prices.…