But the agency did move three years ago to put restrictions on short sales in certain heavily shorted stocks, such as Martha Stewart Living Omnimedia , Krispy Kreme , Overstock.com and FairfaxFinancial .
Whitney Tilson, managing partner at T2 Partners Management in New York City, has been buying shares of FairfaxFinancial (nyse: FFH - news - people ), a Canadian insurer and a favorite target of short-sellers.