Betting on Outcomes Sends Monthly Trading Volumes Soaring to $8.6 Billion, Kalshi Surges to Top Spot

The prediction market sector posted $8.6 billion in taker volume during April 2026, with Kalshi overtaking Polymarket to claim the top spot, according to onchain data tracked by Dune Analytics.

Key Takeaways:

Kalshi posted $5.42B in April 2026 taker volume, surpassing Polymarket’s $1.99B for the first time.

Polymarket collected $29.22M in April fees despite trailing Kalshi in volume, signaling higher-value contracts.

Prediction market open interest hit $1.11B on May 1, 2026, with Kalshi and Polymarket holding 98% of it.

Kalshi Holds $630M in Open Interest as Sector-Wide OI Tops $1.1B at the Start of May

Essentially, prediction markets are platforms where participants buy and sell contracts tied to the outcome of future events, from elections and sports to crypto prices and economic indicators. Contract prices reflect the crowd’s collective probability estimate of an outcome, settling at $1 if correct or $0 if not.

The model has roots stretching back to 19th-century election betting on Wall Street, and gained academic credibility in 1988 when University of Iowa professors launched the Iowa Electronic Markets to test whether crowd-sourced contract prices could outforecast traditional polls. It was realized that they could.

Commercial platforms followed, with Intrade drawing mainstream attention in the 2000s before U.S. legal pressure shut it down. Augur brought the concept to blockchain in the 2010s, though the platform never gained meaningful traction. The real inflection came in the 2020s. Polymarket launched in 2020, built on Polygon and settled in USDC.

The next year, Kalshi received CFTC approval as a Designated Contract Market in 2021, becoming the first federally regulated prediction exchange in U.S. history. The 2024 U.S. presidential election pushed both platforms into mainstream coverage and drove billions in monthly volume. Total 2025 industry volume exceeded $63 billion, and monthly figures peaked near $25.7 billion in March 2026 before April settled at $8.6 billion in taker terms.

Dune Analytics’ data from user @datadashboards, indicates that Kalshi generated $5.42 billion in taker volume last month, giving it a clear lead over Polymarket’s $1.99 billion. The gap between the two platforms has widened considerably since late 2025, when the pair traded closer to parity. Predict.fun ranked third with $579.2 million in April taker volume, followed by Opinion at $376.2 million and Limitless at $205 million. All other platforms combined accounted for roughly $12.2 million.

Image source: Dune

Monthly notional volume across the sector reached $29.8 billion in April, the Dune dashboard shows. Kalshi led that metric as well, logging $14.8 billion. Polymarket posted $9 billion in notional terms, with its separate Polymarket U.S. product contributing an additional $1.26 billion after the platform re-entered the American market legally in late 2025 via the QCEX acquisition.

Prediction market transaction volume highlights an entirely different story. Polymarket processed 87.4 million transactions in April compared to Kalshi’s 94.4 million. The two platforms together accounted for the overwhelming share of the sector’s 184.3 million total monthly transactions.

User counts remained Polymarket‘s clearest advantage. The platform drew 678,342 unique users in April, more than eight times Kalshi’s implied user base. Limitless followed at 71,203 users, with predict.fun at 18,553 and Opinion at 3,423.

Image source: Dune

Open interest across the sector stood at $1.11 billion as of May 1, 2026. Kalshi held $630.7 million of that total while Polymarket carried $449.9 million. Predict.fun, Opinion, and Limitless each held well under $15 million in open positions.

Sector Revenue

Monthly fees generated across the sector reached $31.15 million in April. Polymarket collected $29.22 million of that total, a figure based on resolution price and mergeable amounts. Limitless followed at $1.51 million, with Predict and Opinion generating $260,000 and $154,000 respectively.

The fee figures indicate that Polymarket, despite trailing Kalshi in taker volume, continues to extract a disproportionate share of sector revenue. Its traders appear to place higher-value contracts on average, a pattern consistent with its global user base and deep liquidity on high-profile markets.

April’s numbers extend a growth trend that began accelerating in late 2024. Total monthly taker volume sat below $500 million as recently as mid-2024, meaning the sector has grown more than 17-fold in under two years. Kalshi and Polymarket now control an estimated 85% to 95% of total prediction market industry volume, with academic platforms like PredictIt and the Iowa Electronic Markets operating at a fraction of that scale.