The prediction markets industry continued its cooling-off phase this past week. Combined notional volume across Kalshi and Polymarket Global declined 19.8% week over week to $9.74 billion, marking the first time weekly volume fell below $10 billion since late June.
Kalshi remained the industry’s clear leader despite a 13.5% decline in volume to $7.89 billion. It also expanded its share of comparable trading volume to a record 81.0% — its sixth consecutive week of increased market share and a significant increase from its 68.6% market share at the end of June. So, as overall activity slows, Kalshi eats more of the pie.
Polymarket Global experienced a much steeper decline, with weekly comparable volume falling 38.8% to $1.85 billion — down more than 56% from its mid-July high. This slowdown reflects the fading of political and geopolitical events, highlighting the platform’s dependence on major news headlines.
Meanwhile, Polymarket US showed signs of stabilizing after several weeks of rapid declines. Daily Market Report (DMR) trade volume totaled 866.85 million contracts, down just 0.3% from the prior week after a nearly 30% decline the week before.
| Metric | Kalshi | Polymarket Global | Polymarket US |
|---|---|---|---|
| Comparable USD Volume | $7.89B | $1.85B | N/A |
| Weekly Change | -13.5% | -38.8% | N/A |
| Native Volume | 8.42B contracts | $1.85B | 866.85M contracts |
| Native Volume Change | +6.8% | -38.8% | -0.3% |
| Weekly Transactions | 57.08M | 20.35M | N/A |
Main takeaways?
No more FIFA World Cup, so hello MLB
One of the week’s most notable trends was the disconnect between Kalshi’s dollar volume and overall trading activity. Although USD volume fell 13.5%, Kalshi’s actual number of contracts increased 6.8% to 8.42 billion. This suggests traders remained highly engaged but are looking more at smaller, shorter-duration markets such as Major League Baseball and ATP tennis.
Federal Reserve decision sparks economic trading
Economics became the fastest-growing category of the week as traders focused on the Federal Reserve’s July interest-rate decision. Combined economics-related trading rose 134.4% week over week to $111.01 million. Polymarket Global led the category with $59.43 million, accounting for 53.5% of economics trading. Kalshi generated $42.71 million, while its contract predicting no rate hike produced $11.12 million in weekly volume — up 272.7% — and accumulated $26.04 million in open interest.
This activity showed that major economic events remain one of the few catalysts that can generate significant activity across all major prediction market platforms at the same time.
Polymarket Global continues to dominate news-driven markets
Although overall trading declined, Polymarket Global reinforced its position as the industry’s primary option for politics, geopolitics, and global current events.
The platform captured 74.3% of political trading and 96.5% of the industry’s “Other / Unclassified” category. Markets surrounding tensions between the United States and Iran generated substantial activity, including contracts on a potential U.S. invasion, ceasefire agreements, military operations, and shipping through the Strait of Hormuz.
The platform also continued attracting meaningful activity around niche international events, including League of Legends competitions. This reinforces that one of its strengths is specialized global markets that have limited competition.
Category breakdown
Sports remained the industry’s largest category with $2.97 billion in combined trading volume. Kalshi dominated with 74.5% market share, while Polymarket US accounted for 15.3% and Polymarket Global had 10.2%.
Crypto remained the second-largest category at $1.27 billion, with Kalshi capturing an overwhelming 86.3% share. Both Polymarket platforms experienced notable declines, suggesting crypto activity continues to center on Kalshi.
Politics remained Polymarket Global’s strongest category. The platform generated $73.86 million, representing 74.3% of all political trading. Kalshi accounted for 15.5%, while Polymarket US contributed 10.2%.
Culture and entertainment, though relatively small, boasted one of the strongest growth rates of the week. Combined volume rose 60.5% to $7.66 million, led by Kalshi, while Polymarket US more than doubled its activity from the prior week.
Top market drivers
The week’s highest-volume markets further highlighted the increasingly distinct positioning of each platform.
Kalshi continued to generate most of its liquidity through professional sports. Four of its five largest contracts involved individual MLB or ATP tennis matches, while the Federal Reserve interest-rate decision was the only non-sports market to crack the top five.
Polymarket Global remained centered on major news events. Its largest contract by far was the July Federal Reserve decision, followed by markets tied to U.S.-Iran tensions and international eSports. These results underscore the platform’s continued strength in real-world events that generate bursts of speculative trading.
Polymarket US remained almost entirely sports-focused, with each of its five highest-volume markets involving MLB. Rather than relying on headline-driven events, the platform continues to build around the predictable cadence of daily sports.
What all this means
This week’s slowdown appears more a sign of normalization or regression to the mean than weakening demand. (It can’t always be the FIFA World Cup, after all.) Trading activity was still historically high despite lower overall volumes, while liquidity continued concentrating around the platforms best positioned within their respective specialties.
Kalshi further strengthened its leadership in high-frequency markets and continued gaining market share despite industry-wide declines. Polymarket Global maintained its edge in politics, economics, and breaking news, while Polymarket US showed signs of stabilizing around a sports-focused strategy.
