Contract Watch

What happened. Three venues list a contract on which party wins the Senate on 3 November. Kalshi pays on the party of the President pro tempore of the Senate, as recorded on congress.gov at 10:00 AM ET on 1 February 2027, and can settle earlier once at least four of eight named media desks call the result. Polymarket International and Polymarket US each pay on the party that wins a majority of the Senate's voting seats, and each text lets the market stay open for runoffs and, for undeclared independents, until 11:59 PM ET on 4 January 2027. Their counting rules read almost the same. We read the Polymarket US text on 31 October.

Why it matters. The two Polymarket texts differ in the sources they name and in who decides. Polymarket International names state electoral authorities, the US Congress and a consensus of credible reporting, and resolves through UMA's optimistic oracle, with a token-holder vote if a proposal is disputed twice. Polymarket US names state electoral authorities and the US Senate, and under Rule 10.4 of its rulebook (version dated 30 September 2026) leaves outcome review to named officers whose determinations are final. A dispute over the same Senate result could therefore be settled by different bodies on different evidence.

What happened. Kalshi's contract paid YES if the 60-second average of CF Benchmarks' BRTI before 5:00 p.m. EDT was above $85,499.99. Polymarket International's paid YES if the Binance BTC/USDT one-minute candle closing at noon ET was above $86,000. The BRTI fixing was $81,711.75, and both contracts settled NO.

Why it matters. The contracts differ in source, method, fixing time, quote currency and threshold. On the day, the difference stayed latent. They would have paid opposite sides if both fixings had read between $85,500 and $86,000, or if bitcoin had crossed either threshold between noon and 5:00 p.m.