Polymarket US and Kalshi escalate combo-bet rivalry on same day
Polymarket US launched parlay-style combos to the public Thursday, days after testing the product in an API-only beta. The rollout coincided with Kalshi introducing market-maker fees on its own multi-leg bets the same day. Both platforms hold CFTC registration. Polymarket US cited record July notional volume of $5 billion as momentum for the launch. The parallel moves sharpen direct competition in combination contracts.
Combo-bet fee economics now separate platforms that can attract market makers from those that lose them. Kalshi's new maker fee on multi-leg bets taxes the same liquidity providers Polymarket US is trying to woo with freshly live parlays. The NFL season opens a finite window: whichever venue builds trader habit-formation around combination contracts before January will set the interface and pricing template rivals must match.
Novig's $125 million first-week volume has already reset scale expectations, so parlay traction this quarter shapes fundraising narratives for all three platforms. For traders, the race means more contract variety but also fragmented liquidity until one venue dominates order flow. FanDuel Predicts' stalled five-state pilot shows the cost of missing this product cycle entirely.