Kalshi and Polymarket align within four points on September Fed odds
Kalshi and Polymarket are pricing the September Federal Open Market Committee decision within four percentage points of each other, according to an Investing.com analysis. The comparison examines how prediction market prices function as direct probabilities and where they converge with or diverge from traditional options-implied probabilities. Both platforms display event probability explicitly — a contract priced at 49 cents implies a 49% chance — unlike the more complex derivation required from options markets.
The tight four-point spread matters because it signals both venues are now drawing similar macro flow, not just divergent retail crowds. For traders, convergence narrows the arbitrage window that existed last week, when a 23-point gap rewarded fast settlement across platforms. The alignment also raises execution questions: whichever venue settles faster and publishes deeper book data will capture the institutional desks currently testing prediction markets against CME futures.
Neither platform releases real-time depth, so traders still price opacity into their models. Kalshi and Polymarket diverge sharply on Fed hold odds ahead of rate decision showed how wide spreads hammer the weaker venue's credibility. Sustained convergence on macro contracts would mark a maturation step, but one bad settlement on a surprise hold or hike could reopen the gap and send flow retreating to proven derivatives venues.