Hokkaido Nippon-Ham Fighters vs Saitama Seibu Lions Saitama Seibu Lions
Saitama Seibu Lions win the originally scheduled NPB game. Listed on both Kalshi and Polymarket; recorded continuously since Sep 12, 2026. Live.
Price history, both venues (7 days)
Mid price of the YES side per venue, 5-minute buckets, from continuously recorded order books. Breaks mean the recorder was down or a book was empty.
Recent disagreement windows
| Opened | Closed | Length | Scans | Max net edge |
|---|---|---|---|---|
| Sep 12, 5:02 AM ET | Sep 12, 8:48 AM ET | 3.8 h | 236 | 13.89% |
Related markets on both venues
Frequently asked questions
What are the current Kalshi and Polymarket odds for "Hokkaido Nippon-Ham Fighters vs Saitama Seibu Lions Saitama Seibu Lions"?
As of the latest recorded books, Kalshi's YES mid is 0.0¢ (bid —, ask —) and Polymarket's is 50.5¢ (bid 0.5, ask 0.51) — a —¢ gap. Prices are recorded continuously; this page refreshes every few minutes.
Has this market been an arbitrage?
Yes — 1 separate window where buying the cheaper side on each venue cost less than $1 after both fees, first on Sep 12, 2026 and most recently Sep 12, 2026. The largest net edge was 13.89% and windows averaged 226 minutes.
Do both contracts resolve the same way?
The pair was confirmed as the same question (AI-matched · 95%). That judgment covers the headline question; resolution rules can still differ in edge cases (sources, timing, ties). Read both venues' rules before treating a gap as risk-free.
What do the fees do to the gap?
Kalshi charges takers 7% × price × (1 − price) per contract; Polymarket charges its category rate on the same curve. Near 50¢ that is roughly 1.75¢ per contract on Kalshi and 1–1.75¢ on Polymarket, so a visible gap of 3–4¢ is typically the minimum before anything is left.
← every Kalshi↔Polymarket pair · resolution criteria · taker fees · match: AI-matched · 95%. Verify both markets' rules yourself; this is data, not advice.