A gap between on-chain prediction markets and SOFR futures is opening what traders are calling an arbitrage opportunity ahead of the September FOMC meeting. Traditional interest rate futures tied to SOFR, the benchmark that replaced LIBOR, are implying something closer to 32%. What the numbers actually sayPolymarket participants are also pricing a 63% chance of at least one rate hike from the Fed somewhere in the 2026 calendar year. The question is simply: will the Fed hike or not. Polymarket settles in crypto, operates on-chain, and has counterparty and liquidity dynamics that differ from SOFR futures.