Polymarket’s volume slid for the first time in eight months in April while rival Kalshi set another record, widening a gap that has flipped from near-parity in early March to 59-41 in Kalshi’s favor.

Monthly notional volume on Polymarket’s offshore exchange and US app slipped roughly 9% to $10.3 billion in April, per Bloomberg. Kalshi’s volume rose 13% to a record $14.8 billion.

Kalshi has pulled further ahead since, capturing 72.1% of combined weekly volume in the week ending May 4, per DeFi Rate.

Active Traders Walked Out The Door

Polymarket’s active trader count dropped from roughly 733,000 in March to about 643,000 in April, per data from The Block.

The 12% user decline tracks closely with the volume drop and suggests the slide is not purely a technical artifact.

A Polymarket spokesperson attributed the dip to a V2 upgrade rolled out April 28 that paused trading for an hour and wiped all open orders. “We’ve let people down, and I’m not going to dress that up,” VP of engineering Josh Stevens said.

Founder Shayne Coplan acknowledged at a Harvard event that “there’s been a few times over the course of the business where the way the company ran was suboptimal.”

Kalshi’s Sports Machine Keeps Humming

Sports contracts made up 74.3% of Kalshi’s weekly volume during the week of April 20, rising to about 85% when factoring in its parlay-style “Exotics” product, per The Block. The Masters alone drove $545 million in notional volume on Kalshi, matching its Super Bowl single-game total.

Polymarket’s sports volume, by contrast, fell 7.8% week-over-week through the NBA playoffs.

US App Finally Opens, A Year Late

Polymarket ended its US iOS waitlist Tuesday, more than six months after first accepting bets on its CFTC-registered platform. Coplan claimed in September that the company had a “green light” to launch for the NFL season. It missed the entire NFL regular season, March Madness and The Masters.

Intercontinental Exchange (NYSE:ICE), parent of the NYSE, committed up to $2 billion to Polymarket in a two-stage deal completed in March at an $8 billion pre-money valuation.

Polymarket is reportedly in talks to raise an additional $400 million at a $15 billion valuation, though Kalshi raised at $22 billion in March.

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