Hedge funds hiked their bets against Facebook through last week as CEO Mark Zuckerberg got set to testify in front of Congress following a data scandal, according to data from IHS Markit. IHS Markit forecasts short interest in Facebook to have totaled 29.2 million shares on Friday, up from 25.9 million in mid-March. That's still a small amount relative to the shares available for trading on the social media stock, but it indicates that some hedge funds could be looking to capitalize on any stumbles as Zuckerberg looks to repair the company's reputation.