Boston-based private equity firm Advent International has agreed to buy a majority stake in AOT Bedding Super Holdings, the parent company of National Bedding Co. (the majority owner and licensee of Hoffman Estates, Ill.-based Serta) and Atlanta-based Simmons Bedding Co.

Terms of the deal were not disclosed by the parties involved, but an Aug. 5 Reuters story values the AOT transaction at about $3 billion, including debt. Advent prevailed over other private equity bidders, such as Bain Capital and Berkshire Partners, according to one Reuters source.