Kalshi Locks Up the US Open Two Days After a Nevada Defeat

Kalshi is the exclusive prediction-market partner of the US Open. The arrangement took effect as the main draw opened on Sunday at Flushing Meadows in New York, and Front Office Sports reported it first that day. Neither the company nor the United States Tennis Association put a price on it. The USTA had planned to look at prediction-market partnerships for 2027 and later, and moved a year early instead. Two days before the deal surfaced, a federal appeals court ruled against Kalshi in Nevada.

The clause that does the work

What the agreement blocks matters more than what it grants. Competing prediction-market platforms cannot advertise at the venue or on ESPN's broadcasts, a term Front Office Sports described as unusual and three other outlets repeated. ESPN holds US Open rights through a 12-year agreement running to 2037, a detail Blockonomi carries alone. The deal was finalized after qualifying rounds ended the previous week. Craig Tiley, the USTA's chief executive since 20 July and formerly the head of Tennis Australia, is named in every account as the person who accelerated it.

One detail sits oddly beside the word exclusive. As of Sunday afternoon Kalshi was not listed among the US Open's official partners, and the company was carrying a disclaimer of its own saying it is "not affiliated with the U.S. Open or WTA." The Block reported both. Kalshi and ESPN declined to comment to Front Office Sports, and the USTA did not comment either. The terms come from one report, confirmed by nobody in it.

Volumes, each from a single desk

The trading figures are large and thinly sourced. The Block puts August volume across Kalshi, Polymarket and Polymarket US at $41.2 billion, of which Kalshi accounts for $33.7 billion; that split appears in no other account located. crypto.news reports some individual match contracts passing $1 million on the first day, and puts Kalshi's record weekly volume at $5.1 billion in June. Front Office Sports counted about $1.5 million traded on women's singles outcomes by Sunday afternoon, with Aryna Sabalenka the favorite at 23%. Blockonomi adds five MLB club deals announced on 25 August. Each number stands in the outlet that published it.

Nevada, and the split the ruling opens

On 28 August the US Court of Appeals for the Ninth Circuit upheld a district court's decision to dissolve a preliminary injunction against the Nevada Gaming Control Board, which had sent Kalshi a cease-and-desist letter in 2025. The panel held the company had not shown the federal Commodity Exchange Act displaces state gaming rules for sports event contracts.

"We conclude that Kalshi has not shown a likelihood that the CEA preempts state gaming regulations," the appeals court wrote, in the passage carried by The Block on Friday.

That is the opposite of what the Third Circuit held in April, when it found New Jersey could not apply its gambling laws to the same federally regulated contracts. Two circuits now disagree on the same question. A CFTC spokesperson, Zach Fulton, said the Ninth Circuit "erred today when it invented a new and textual exception to the CEA," and the agency said the case had teed up a split calling for Supreme Court resolution. Kalshi's spokesperson, Dani Lever, said the company would be "seeking further review." The state-court record already runs against it: a Connecticut judge ruled in August that the sports contracts were never swaps, and crypto.news reports that Baltimore sued Kalshi and Polymarket on 13 August over unlicensed sports betting, an item this desk found in that account only.

Where this lands next

The tournament runs a fortnight, and the exclusivity runs with it. What the ruling changes is slower. A circuit split is the classic condition for Supreme Court review, and both the CFTC and Kalshi have said they want the question taken further, though neither has filed. Nothing in the Nevada decision touches New York, where the US Open is played, and the federal filing rules for these products were tightened separately this year. What a first exclusive tennis deal is worth will show up in the volume series, and August closed before the main draw did.