Sports prediction markets moved sharply this week as the NFL passed the quarter mark, the NBA regular season prepared to tip off, and Major League Baseball’s playoff bracket came into focus. The biggest single move: the Buffalo Bills climbed to a 19% implied probability of winning Super Bowl LXI on Kalshi after a 4-0 start, overtaking the Kansas City Chiefs (16%) as the top-priced AFC contender for the first time since the 2022 season. Below is a breakdown of where the action is heading into the final week of September.
NFL: Bills Overtake Chiefs, Lions Steady in NFC
Through four weeks, contract volume on the Super Bowl LXI market crossed $74 million across Kalshi and Polymarket combined, the highest late-September figure in the market’s history. Buffalo’s 4-0 start plus a +54 point differential drove the biggest reprice of the young season. On the NFC side, the Detroit Lions held firm at 17% to win the conference, with the Philadelphia Eagles at 14% and the San Francisco 49ers at 12%. Notable movers this week:
- Buffalo Bills to win Super Bowl: 14% → 19% (+5 pts)
- Kansas City Chiefs to win Super Bowl: 19% → 16% (-3 pts)
- Miami Dolphins to make playoffs: 41% → 28% (-13 pts, after 0-4 start)
- Baltimore Ravens to win AFC North: 44% → 51% (+7 pts)
MVP contracts also churned. Josh Allen leads the field at 22%, followed by Lamar Jackson at 15%, Jayden Daniels at 11%, and Patrick Mahomes at 9%. Traders on Polymarket are pricing a wide-open race, with the “field” (any other player) still commanding roughly 43% of the market.
NBA: Celtics and Thunder Split the Board
With opening night nine days away, NBA championship futures are settling into a top-heavy shape. The Oklahoma City Thunder — defending champions — hold the shortest price at 18% to repeat, matched by the Boston Celtics at 18%. The Denver Nuggets sit third at 12%, with the New York Knicks and Minnesota Timberwolves each near 8%.
Prediction markets are less confident than Vegas on OKC. Sportsbook implied odds put the Thunder closer to 22% to win the title, meaning Kalshi and Polymarket traders see roughly four points of value against the field. The gap widens in the West, where the Los Angeles Lakers trade at 6% on prediction markets versus roughly 9% at traditional books. Rookie of the Year action has also picked up: Cooper Flagg is a heavy 58% favorite, with Ace Bailey a distant second at 11%.
MLB: Playoff Picture Locks In
The regular season ends this weekend, and prediction markets have already crystallized the postseason bracket. The Los Angeles Dodgers remain the World Series favorite at 22%, though their price has slipped from 27% at the trade deadline as the pitching staff worked through late-season injuries. The Philadelphia Phillies (14%) and New York Yankees (13%) round out the top three.
Wild card intrigue is driving late-week volume. The New York Mets sit at 71% to lock the final NL wild card, up from 48% a week ago after taking three of four from Atlanta. In the AL, the Seattle Mariners jumped to 84% to hold the top wild card seed following a sweep of the Astros. Full division futures now stand at:
| Division | Leader | Implied Probability |
|---|---|---|
| AL East | Yankees | 96% |
| AL Central | Guardians | 89% |
| AL West | Mariners | 78% |
| NL East | Phillies | 92% |
| NL Central | Cubs | 67% |
| NL West | Dodgers | 99% |
Cy Young futures have narrowed. Tarik Skubal is the runaway AL favorite at 81%, while the NL race between Paul Skenes (46%) and Zack Wheeler (33%) is the tightest individual-award market on the board.
Cross-Sport Volume and What to Watch
Total sports-contract volume across Kalshi and Polymarket topped $210 million for the week ending September 27, with NFL accounting for roughly 62% of the flow. Sharp traders are watching three catalysts in the next seven days: the NFL trade deadline chatter as 0-4 teams weigh sellers’ markets, the NBA opening-night injury reports, and the final MLB Cy Young start for Skubal on Saturday.
Where to Trade
Both major US prediction market venues are offering deep books on this week’s sports contracts. Kalshi holds the widest range of federally regulated sports event contracts, including single-game outcomes, division futures, and MVP markets. Polymarket offers larger championship-futures liquidity and pairs it with head-to-head player prop markets.
For a full comparison of fees, sports coverage, and liquidity across every major prediction market platform, see our 2026 rankings of the best prediction markets.