Prediction markets had another strong week from Aug. 24-30, with activity led by Kalshi on sports and continued interest in macroeconomic and esports markets on Polymarket Global.
Combined contract volume across Kalshi and Polymarket Global reached $11.26 billion, up 9.3% week over week from $10.30 billion the previous week. The two platforms generated $3.40 billion in combined volume, a modest 0.5% increase.
The number of completed trades moved in the opposite direction, falling 2.9% to 75.21 million.
Kalshi was responsible for most of the week’s growth. The platform crossed $10 billion in weekly contract volume for the first time in August, recording $10.17 billion in contract volume, up 12.2% WoW. It also generated $2.83 billion in volume, up 3.3%.
That gave Kalshi 90.3% of combined contract volume across the two platforms.
Polymarket Global, meanwhile, recorded $1.09 billion in contract volume, down 11.9% week over week, and $561.91 million in volume, down 11.4%.
Polymarket US recorded $742.08 million in contract volume from Aug. 24-29. Aug. 30 data was still pending from the platform’s official Daily Market Reports.
Weekly contract volume reaches $11.26 billion
| Metric | Kalshi | Polymarket Global | Polymarket US | Combined (K + PMG) |
|---|---|---|---|---|
| Contract Volume | $10,169,908,020 +12.2% WoW | $1,086,735,664 -11.9% WoW | $742,080,305* Partial 6/7 reports | $11,256,643,684 +9.3% WoW |
| Execution USD Volume | $2,834,314,916 +3.3% WoW | $561,911,830 -11.4% WoW | Unavailable | $3,396,226,746 +0.5% WoW |
| Total Transactions | 63,369,113 -1.2% WoW | 11,853,087 -11.3% WoW | Unavailable | 75,222,200 -2.9% WoW |
| Volume Share | 90.3% +2.3 pts WoW | 9.7% -2.3 pts WoW | Excluded | 100.0% |
| Open Interest (Snapshot) | 787,106,260 | 230,217,704 | 117,037,747 | Not additive |
*Polymarket US contract volume reflects partial 6/7 official Daily Market Reports (August 24–29; August 30 pending) and is excluded from combined totals due to metric definition differences.
Kalshi accounts for 88.6% of $3.07 billion in sports volume
| Category | Kalshi | Polymarket Global | Combined (K + PMG) |
|---|---|---|---|
| Other / Uncategorized | $5,344,799,136 92.4% share | $440,397,837 7.6% share | $5,785,196,973 |
| Sports | $2,724,145,859 88.6% share | $348,841,186 11.4% share | $3,072,987,046 |
| Crypto | $1,859,135,321 89.9% share | $208,348,981 10.1% share | $2,067,484,302 |
| Economics / Finance | $178,584,624 85.7% share | $29,786,203 14.3% share | $208,370,827 |
| Politics | $58,991,339 52.4% share | $53,594,570 47.6% share | $112,585,910 |
| Culture / Entertainment | $4,251,740 42.4% share | $5,766,886 57.6% share | $10,018,627 |
Kalshi: PGA Tour Championship, combos, and football is back
Kalshi’s record-setting week was driven primarily by sports markets and increasingly popular multi-leg structured products.
- TOUR Championship Winner: The PGA TOUR Championship winner market was the single biggest market across the platforms this week. It settled after generating $91.19 million in contract volume.
- Multi-leg combo volume: Combo markets were another major source of activity for Kalshi. A multi-game MLB combo involving Miami, Detroit, Washington, Texas, Los Angeles (Angels) and Chicago (Cubs) generated $36.80 million in contract volume. Newly listed combos covering Mexican Liga MX soccer, MLB matchups, and European soccer also performed well, occupying four of Kalshi’s top 10 market slots. Overall, Kalshi’s combo volume increased 14.2% week over week to $1.29 billion in contract volume.
- NFL preseason surge: The return of football drove more trading across NFL markets. The matchup between Seattle and Tennessee generated $20.15 million in contract volume, while the Rams vs. the Chargers reached $17.63 million in contract volume.
- College football markets saw big action too. Memphis vs. UNLV drew $17.78 million in contract volume, while North Carolina vs. TCU attracted $17.67 million in contract volume.
- Political markets were quieter by comparison, but Kalshi’s 2028 Democratic Presidential Nominee market still grew 129.3% week over week to $14.93 million in contract volume amid a broader shakeup in the 2028 Democratic field.
Polymarket Global: Fed rate decision, Brazilian election
Polymarket Global had a noticeably different mix of activity, with macroeconomic markets and competitive gaming standing out.
- September Fed decision: The platform’s top market was “Fed Decision in September?”, which generated $19.57 million in contract volume, up 33.9% week over week.
- Esports activity: A Counter-Strike match between Team Falcons and Lynn Vision at BLAST Open Porto generated $10.97 million in contract volume. League of Legends matches were also heavily represented, accounting for five of the platform’s top 10 markets. KT Rolster vs. HANJIN BRION led that group with $8.49 million in contract volume. T1 vs. BNK FEARX generated another $8.33 million in contract volume, while Top Esports vs. LGD Gaming reached $7.82 million in contract volume.
- Crypto and politics: Crypto remained another significant source of activity. The “What price will Bitcoin hit in August?” market generated $9.80 million in contract volume, although that was down 10.4% week over week.
- Brazil’s presidential election market moved in the opposite direction, growing 22.8% to $8.65 million in contract volume.
Polymarket US: MLB, MLB, and more MLB
Trading on Polymarket US through Aug. 29 was concentrated primarily in individual MLB games, along with NFL preseason markets.
The biggest market was Pittsburgh Pirates vs. San Diego Padres on Aug. 25, which generated $5.99 million in contract volume.
Two Boston Red Sox vs. Miami Marlins markets followed closely behind, with the Aug. 24 game generating $4.87 million in contract volume and the Aug. 25 matchup producing another $4.39 million in contract volume.
Category breakdown
- Sports: Sports generated more than $3.07 billion in contract volume across Kalshi and Polymarket Global. Kalshi accounted for 88.6% of that volume, with $2.72 billion in contract volume, although its sports volume fell 3.8% week over week. Polymarket Global reached $348.84 million, up 29.6%.
- Crypto: Kalshi also dominated crypto, generating $1.86 billion in contract volume, representing an 89.9% share. Polymarket Global recorded $208.35 million in crypto contract volume, down 11.1%. Polymarket US added another $145.29 million in contract volume.
- Economics and finance: Economic markets were among the fastest-growing categories on both major platforms. Kalshi’s volume increased 35.0% to $178.58 million in contract volume, while Polymarket Global grew 25.6% to $29.79 million in contract volume. The gains came as traders increasingly focused on upcoming Federal Reserve policy decisions.
- Politics: Political markets saw a pullback on both platforms. Kalshi’s political volume declined 28.9% to $58.99 million in contract volume, while Polymarket Global fell 26.6% to $53.59 million in contract volume. Kalshi held a 52.4% share of the combined category.
- Culture and entertainment: Culture markets posted strong percentage gains despite remaining relatively small. Kalshi volume increased 34.9% to $4.25 million in contract volume, while Polymarket Global rose 28.2% to $5.77 million in contract volume. Polymarket Global held a rare majority in the category, accounting for 57.6% of combined volume.
Growth of 25% in 6 weeks
Weekly volume across Kalshi and Polymarket Global increased from $9.00 billion for the week ending July 26 to $11.26 billion for the week ending Aug. 30.
That’s a 25.1% increase in just six weeks.
Kalshi’s share also steadily increased over the period:
- July 26: 87.6% — $7.88B Kalshi vs. $1.12B Polymarket Global
- Aug. 2: 88.3% — $8.42B vs. $1.11B
- Aug. 9: 88.9% — $8.07B vs. $1.01B
- Aug. 16: 88.7% — $8.67B vs. $1.11B
- Aug. 23: 88.0% — $9.06B vs. $1.23B
- Aug. 30: 90.3% — $10.17B vs. $1.09B
The latest week marked Kalshi’s strongest share of the six-week period and the first time it surpassed 90%.
