Properly Reducing Overexemptions for Sports Act or the PRO Sports Act - Amends the Internal Revenue Code to remove professional football leagues from the list of tax-exempt organizations.

Provides that no organization or entity shall be treated as tax-exempt if it: (1) is a professional sports league, organization, or association, a substantial activity of which is to foster national or international professional sports competitions (including by managing league business affairs, officiating or providing referees, coordinating schedules, managing sponsorships or broadcast sales, operating loan programs for competition facilities, or overseeing player conduct); and (2) has annual gross receipts in excess of $10 million.