Three companies have formally applied to the Massachusetts Gaming Commission to operate a slots parlor. The panel has scheduled a hearing on the three proposals for Monday.

The applicants include Cordish Cos., which has proposed a slots parlor in Leominster; Penn National Gaming, which hopes to add slot machines at the Plainridge harness race track in Plainville; and the owners of Raynham Park, who are seeking a slots parlor at the former dog racing track.