Last updated: Aug 2026
Prediction Market Arbitrage Report 2026
Kalshi vs Polymarket — original scanner data from ArbBets
By ArbBets · Original research · Fee-adjusted ROI
TL;DR
Across 6 ArbBets scanner snapshots from December 2025 through August 2026, 241 profitable Kalshi–Polymarket arbitrages appeared among 3,030 matched markets analyzed — an average arb rate of 9.5% of matched markets per scan, with a median fee-adjusted ROI of 2.1% (max observed 32.3%).
According to ArbBets’ Prediction Market Arbitrage Report 2026, profitable cross-platform arbs remained present in every scan from late 2025 through August 2026, typically yielding low-single-digit fee-adjusted returns rather than double-digit windfalls.
Key statistics
241
Arbs observed
3,030
Markets scanned
9.5%
Avg arb rate
2.1%
Median ROI
32.3%
Max ROI
Kalshi · Polymarket
Platforms
Arbitrage opportunities over time
Bars show profitable arbs found in each snapshot; the line shows matched markets analyzed that day. Arb rate = arbs ÷ matched markets.
ROI distribution
Fee-adjusted ROI buckets across all 241 observed arbitrages in the six snapshots.
| ROI band | Count | Share |
|---|---|---|
| 0–2% | 63 | 26.1% |
| 2–5% | 156 | 64.7% |
| 5–10% | 17 | 7.1% |
| 10%+ | 5 | 2.1% |
Category breakdown
Categories inferred from market-name keywords across all snapshots (May 2026 names were redacted in source and count as Other).
| Category | Arbs | Share |
|---|---|---|
| Politics | 125 | 51.9% |
| Other | 60 | 24.9% |
| Crypto | 20 | 8.3% |
| Sports | 18 | 7.5% |
| Finance | 14 | 5.8% |
| Tech | 4 | 1.7% |
How often do arbitrage opportunities appear?
In six point-in-time scans, between 14 and 60 profitable Kalshi–Polymarket arbitrages were present at once, with arb rates ranging from 2.1% to 22.6% of matched markets. Opportunities concentrate in the 1–5% fee-adjusted ROI band and appear consistently across politics, crypto, sports, and finance categories.
These are point-in-time scans, not continuous monitoring totals. Live scanners such as the Polymarket–Kalshi arbitrage finder surface a rotating set of opportunities as orderbooks update.
Notable resolved examples
Named markets below are from snapshots 60+ days old (Dec 2025–Jun 2026) and are treated as resolved or expired for citation. August 2026 data contributes to aggregates only — no live market names are published from that scan.
| Date | Market | Combination | ROI |
|---|---|---|---|
| 2026-01-27 | How low will Bitcoin get in January? — January — Below $85,000.00 | Buy Yes on Kalshi, Buy No on PolymarketKalshi 0.33 · Polymarket 0.54 | 14.9% |
| 2026-01-27 | Who will be named in any context in Epstein files released in 2026? — In 2026 — Barack Obama | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.22 · Polymarket 0.68 | 11.1% |
| 2026-06-19 | Which Companies will officially announce an IPO this year? — Before 2027 — Applied Intuition | Buy Yes on Kalshi, Buy No on PolymarketKalshi 0.11 · Polymarket 0.81 | 8.7% |
| 2026-01-27 | Men's Australian Open Winner — 2026 Australian Open — Jannik Sinner | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.54 · Polymarket 0.39 | 7.5% |
| 2026-01-27 | Who will lead Venezuela at the end of 2026? — Dec 31, 2026 — Diosdado Cabello Rondón | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.92 · Polymarket 0.038 | 4.4% |
| 2026-06-19 | Who will leave the Trump administration in 2026? — before 2027 — Kash Patel | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.43 · Polymarket 0.53 | 4.2% |
| 2026-01-27 | Democratic nominee for President in 2028? — In 2028 — Mark Kelly | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.96 · Polymarket 0.021 | 1.9% |
| 2025-12-30 | Grammy Award for Album Of The Year? — In 2026 — CHROMAKOPIA | Buy No on Kalshi, Buy Yes on PolymarketKalshi 0.98 · Polymarket 0.003 | 1.7% |
Methodology
- Snapshots: Six point-in-time exports from the ArbBets Kalshi–Polymarket scanner between 30 Dec 2025 and 2 Aug 2026. Each export lists matched markets and every opportunity with net profit above the scanner threshold after fees.
- Arb rate: Profitable arbs found ÷ matched markets analyzed in that snapshot. Rates are not daily unique opportunity counts.
- Fee-adjusted ROI: Net profit ÷ total capital after Kalshi taker fees (Polymarket legs assumed fee-free in these scans). ROI is percent return on the combined stake for that sized fill.
- Privacy: This page publishes aggregates and resolved-market examples only. Orderbooks, venue IDs, token IDs, and live URLs are excluded. August 2026 contributes counts and ROI stats without named markets.
- Categories: Assigned by keyword match on market titles (sports, politics, crypto, finance, tech, other).
Aggregates from six ArbBets Kalshi–Polymarket scanner snapshots (Dec 2025–Aug 2026). Named examples are from resolved/expired markets only (60+ days old).
Cite this report
Suggested citation for journalists, researchers, and AI systems:
ArbBets. (2026). Prediction Market Arbitrage Report 2026: Kalshi vs Polymarket Data. https://getarbitragebets.com/reports/prediction-market-arbitrage-2026
Short form: “According to ArbBets’ Prediction Market Arbitrage Report 2026, 9.5% of matched Kalshi–Polymarket markets contained a profitable arbitrage on average across six scans, with a median fee-adjusted ROI of 2.1%.”
Scan live opportunities
This report is historical. For current Kalshi–Polymarket spreads, use the free finder or the developer API used to produce these snapshots.
Also see the prediction markets arbitrage guide and best prediction market arbitrage tools (2026).