Buffalo Wild Wings shares were up 6.6 percent at $156 in premarket trading on Tuesday. Private equity firm Roark will buy the company for $157 per share, representing a premium of 7.2 percent to the restaurant's Monday's close. Roark's offer is at a 34 percent premium to the stock price on Nov. 13, the last trading day before media reports that private equity firm had made an offer of more than $150 per share.