Mattress Firm Holding Corp. (MFRM) has reached a deal to acquire fellow mattress retailer Sleepy's in a $780 million deal that will combine the largest mattress specialty retailers in the U.S. Mattress Firm will acquire Sleepy's parent company, HMK MAttress Holdings LLC, for about $740 million of cash and debt, about $30 million of quantified liabilities assumed, and up to $10 million of rollover equity. Mattress Firm for many years had thought a combination of the two industry players 'needed to happen,' Mattress Firm CEO Steve Stagner said on a Monday call with investors after the close of regular trading. He indicated that conversations about a possible deal had been discussed over the years, The Deal's Senior Reporter Sarah Pringle reported.