Apollo Global Management is suing private-equity firm Advent International in a dispute over how to financially restructure the Advent-owned Serta Simmons Bedding LLC, the largest mattress maker in the US.

Hedge-fund managers Apollo, Angelo Gordon & Co. and Gamut Capital Management LP, who own some of Serta’s corporate loans, filed a suit 11 June against Serta and Advent in New York State Supreme Court.