If John Mayer is or if it is announced that John Mayer is the Headliner at Coachella 2027, then the market resolves to Yes. To fulfill the Payout Criterion, the specified person must actually appear and carry out the specified role at the event. Being listed in the official lineup without actually performing does not qualify. Joint performances where the person shares the role with another performer do count. The performance qualifies even if delayed, shortened, or modified in format. Pre-recorded content does not qualify unless explicitly designated by organizers as fulfilling the role. Rumored or unofficial announcements, canceled appearances, and performances in different roles than specified do not satisfy the criterion. This market will close and expire early if the specified performance occurs.