Prediction markets exploded in 2025. Two platforms, Polymarket and Kalshi, together dominate the entire landscape, with a combined monthly volume that routinely exceeds $15 billion as of early 2026.
What started as niche platforms for political gambling have matured into serious financial infrastructure, but they differ fundamentally in architecture, user base, and where the growth is coming from.
In February 2026, Kalshi processed a record $9.8 billion in monthly volume while Polymarket hit its own record of $7 billion, a 7.5× year-over-year increase. Both are growing explosively, but Kalshi has now pulled ahead in raw volume.
Volume Stats at a Glance
Monthly Trading Volume (Jan 2025 – Feb 2026)
Both platforms were relatively flat through mid-2025, hovering around $0.8–1.2B per month, before an explosive Q4 surge driven by major geopolitical and sports events. Kalshi’s jump was steeper and earlier.
Source: Dune Analytics, KalshiData, The Block | *Q1–Q3 estimates based on annual totals
Key Platform Metrics
| Metric | Polymarket | Kalshi |
|---|---|---|
| Founded | 2020 | 2021 |
| 2025 Annual Volume | ~$18B (cumulative) | $23.8B |
| Feb 2026 Monthly Volume | $7.0B | $9.8B |
| All-Time Daily Record | $425M (Feb 28, 2026) | $381.7M (Dec 21, 2025) |
| Open Interest (Jan 31, 2026) | ~$400M | ~$400M |
| YoY Growth (2024→2025) | ~700%+ | 1,108% |
| 2025 Total Transactions | — | 97 million |
| Active Traders (peak) | 477,850/month | ~400,000 DAU (Nov 2024 peak) |
| Markets Available | 500+ | 200+ |
Open interest was essentially tied at ~$400M each as of January 31, 2026, making them genuinely competitive at the top of the book. Kalshi’s peak OI hit $533M during a single high-activity day in 2025.
The Q4 2025 Inflection Point
Both platforms were growing steadily through the first half of 2025, but October 2025 marked a clear inflection point.
Polymarket’s monthly volume jumped from $1.4B in September to $3.02B in October, a 110% monthly increase, as 477,850 active traders poured in, partly fueled by speculation around a POLY token airdrop.
Kalshi’s Q4 was even more dramatic: October volume was ~$4.4B, November hit $5.8B, and December set a monthly record of $6.38B. Kalshi opened 2026 on January 1 alone with $291M in a single day, nearly double December 1’s $147M.
Kalshi’s 2025 growth of 1,108% YoY and 97 million total transactions represent arguably the fastest scaling of any regulated financial exchange in recent history.
Rootdata.com
Growth Trajectory
The flat-then-vertical growth pattern is unmistakable. Both platforms were in a “base-building” phase from Feb–Aug 2025, then surged simultaneously in Q4.
Source: KalshiData, Dune Analytics | Kalshi leads in absolute volume since Oct 2025
tradetheoutcome.com
Fee Structure
| Fee Type | Polymarket | Kalshi |
|---|---|---|
| Trading Fee | ~2% on net winnings only | $0.01–$0.07 per contract (upfront) |
| Fee on Losing Trades | $0 | Yes (paid upfront) |
| Deposit Fee | $0 (USDC) | $0 (ACH) |
| Withdrawal | $0 + minor gas | $0 |
| Card Deposit | ~3.5% via MoonPay | Supported (fees vary) |
tradetheoutcome.com
For casual traders or those with mixed win rates, Polymarket’s “only pay on wins” model is more forgiving. For high-volume traders with strong win rates in specific markets, Kalshi’s per-contract fee can be cheaper overall.
Regulation, Access & Trust
| Factor | Polymarket | Kalshi |
|---|---|---|
| Regulatory Status | Unregulated / Decentralized | CFTC-regulated (DCM status) |
| U.S. Residents | Geo-blocked | Legal access |
| KYC Required | No | Yes |
| Custody | Self-custody (USDC wallet) | Kalshi holds funds |
| Blockchain | Polygon (EVM-compatible) | None (centralized) |
Tradetheoutcome.com
This is where Kalshi’s edge is structural and durable. Its CFTC designation means institutional capital can flow in without legal risk, a massive liquidity advantage that Polymarket simply cannot match for U.S.-based participants.
The Double-Counting Problem
A critical caveat: Paradigm published a detailed analysis in December 2025 noting that Polymarket’s reported volume is being double-counted in many dashboards, including widely cited on-chain trackers, because certain NegRisk market structures record both sides of a trade as independent transactions.
This means Polymarket’s true volume figures may be inflated relative to Kalshi’s more straightforward fiat-based accounting. Take absolute volume comparisons with a grain of salt.
Who Should Use Which?
- Polymarket is better for: global traders outside the U.S., crypto-native users, broad market variety (500+ markets), and those who want no-KYC access with self-custody of funds.
- Kalshi is better for: U.S. residents who need legal compliance, traders focused on U.S. economic data and sports, institutional investors, and anyone who prefers fiat (USD) without blockchain complexity.
The prediction market duopoly is real, and both platforms are still early in their growth curves. Kalshi’s regulatory moat makes it the institutional favorite going into 2026, while Polymarket’s global, permissionless design keeps it the go-to platform for the rest of the world.
