Kalshi signs as exclusive prediction market partner of the US Open

Kalshi has secured an exclusive prediction market partnership with the US Open tennis tournament, according to a report published August 30. Under the terms of the agreement, competing prediction market platforms are barred from advertising at the tournament and from ESPN broadcasts of the event.

The deal extends Kalshi's sports partnership strategy into tennis at a moment when the company's legal standing varies by jurisdiction. The Third Circuit has held in Kalshi's favor while the Ninth Circuit ruled against it, leaving the question of federal preemption unresolved pending Supreme Court review. State-level enforcement actions remain active in Connecticut, Montana, Nevada, and elsewhere.

An exclusive broadcast advertising bar is a more aggressive commercial position than a standard sponsorship. It forces rivals off one of the sport's most-watched platforms during the tournament window — a direct competitive move in a market where Polymarket holds the MLB league-wide deal and has agreements spanning more than 20 leagues through its Sportradar partnership.