Boston Red Sox vs. Tampa Bay Rays odds: Kalshi vs Polymarket
Fri, Sep 18, 2026, 7:10 PM ET · MLB games · $5 traded in 24h across both venues.
Tampa Bay Rays: Kalshi 54¢ vs Polymarket 54¢, +0.5 pp
Mid prices. A price is the market's probability: 54¢ means 54%. The gap is Kalshi minus Polymarket in percentage points.
Two separate exchanges, two accounts. Links may carry a referral code, which never changes what is shown. Disclosures.
-5.24¢ per $1, after fees
Buy Boston Red Sox @ Kalshi 47¢, Tampa Bay Rays @ Polymarket 55¢
All outcomes
| Outcome | Kalshi bid / ask | Polymarket bid / ask | Gap |
|---|---|---|---|
| Boston Red Sox | 43¢ / 47¢ | 45¢ / 48¢ | -1.5 pp |
| Tampa Bay Rays | 53¢ / 55¢ | 52¢ / 55¢ | +0.5 pp |
Price history, last 3 days
How this is matched
Games are matched across the two exchanges by league, team codes and date. Polymarket prices come from its live order book, Kalshi from its public API. Refreshed every 45 seconds.
What this is not
Read-only. Nothing here places or routes orders and nothing is advice. Fees, slippage and the time it takes to move money between venues are not in these numbers.