The antitrust theory known as “foreclosure” could determine whether mattress manufacturer Tempur Sealy is allowed to complete its proposed $4 billion acquisition of retailer Mattress Firm.

The Federal Trade Commission has a “pretty solid” basis for opposing Tempur Sealy’s proposed vertical merger, according to antitrust law scholar Harry First, but another antitrust expert suggests it could be “challenging” for the FTC to win the foreclosure argument in court.