Polymarket & Kalshi: Rule Changes vs. Volume Surge Amid Regulatory Scrutiny

The prediction market industry is showing explosive growth, with total notional volume rebounding to $5.80 billion for the week of Feb. 23–March 1, a 10.4% weekly gain. This surge is driven by a standout performance from Polymarket, which posted a 31.9% weekly jump to $2.40 billion-its largest weekly showing since late January.

That volume is translating into massive transaction activity, with the two largest platforms recording 44.4 million transactions for the week. Polymarket leads in volume and transaction count, handling 24.6 million of those transactions and closing the gap on its rival, Kalshi.

This multi-faceted growth-spiking weekly volume, soaring transaction counts, and a strong monthly total of $22.3 billion-demonstrates a market in motion. It's building deep liquidity, but this rapid expansion is unfolding against a backdrop of heightened regulatory scrutiny, setting the stage for a critical tension.

The Rule Changes: A Reactive Defense

The new market integrity measures are a direct, reactive response to intense regulatory scrutiny. Both Polymarket and Kalshi have updated their rules to explicitly prohibit trades based on "stolen confidential information" or illegal tips, and to bar users who "hold a position of authority or influence" that could sway an event's outcome. These changes apply to both U.S. and offshore operations, aiming to create a uniform standard.

Kalshi is taking a more preventative approach, introducing screening tools to block political candidates from wagering on their own campaigns and athletes from betting on their own sports. This shift from reactive investigations to proactive screening is designed to address high-profile, suspiciously timed bets that have sparked political accusations. The timing is clear: these changes follow a recent spate of well-timed, highly profitable wagers that raised serious insider trading concerns.

The pressure is coming from multiple fronts. Lawmakers have introduced bills to ban members of Congress from trading, citing incidents like a $553,000 win on a bet about an Iran strike. Reports of massive, accurate bets on events like the capture of a Venezuelan president have further fueled the fire. In this environment, the rule updates are less about future-proofing and more about defending against immediate regulatory and political attacks.

Catalysts and Risks: The Regulatory Crossroads

The most immediate forward pressure is regulatory clarity-or the lack thereof. The Commodity Futures Trading Commission is actively soliciting public comment on how its rules apply to prediction markets, with a deadline of April 30, 2026. This Advance Notice of Proposed Rulemaking will shape the future compliance burden for platforms, covering everything from margin requirements to anti-manipulation rules. The outcome of this process is a major overhang on the industry's growth trajectory.

Legislative risk is also materializing. A U.S. Senate bill has been introduced to ban sports betting on prediction markets, directly targeting a core product line. This follows a pattern of political scrutiny, including a recent $553,000 win on a bet about an Iran strike, which fueled accusations of insider trading. The market's explosive growth is fueled by these same high-stakes geopolitical events, with a single week's volume on Iran strike markets reaching over $17 million.

The bottom line is a market caught between powerful catalysts and significant risks. The surge in volume, driven by events like the Iran strikes, shows immense demand. Yet the regulatory and legislative crossroads ahead could impose new costs, restrictions, or even carve out entire market segments, testing the industry's ability to scale under a cloud of uncertainty.