Kalshi Hits Record $19 Billion Week As Polymarket US Triples Fall Trade Volume
Kalshi reached $19.03 billion in weekly contract volume Oct. 5-11. Polymarket US Trade Volume nearly tripled in six weeks.
Kalshi's weekly contract volume climbed to $19.03 billion for Oct. 5-11, 2026, the highest of the six weekly totals reviewed.
Polymarket US rebounded to 2.82 billion in reported Trade Volume, while Polymarket recorded $498.81 million in cash-dollar volume.
Weekend trading accounted for a large share of activity. Kalshi's contract volume rose across the six-week series, while Polymarket US recovered from the previous week's decline. The venue-wide totals don't show how much of the increase came from NFL or college football.
Top-line performance
Kalshi recorded $19.03 billion in weekly contract volume from Oct. 5-11, up 3.57% from the previous week. Polymarket US reported 2.82 billion in Trade Volume, up 4.25% from 2.71 billion the week before. Polymarket recorded $498.81 million in cash-dollar volume, down 3.89% from $519.01 million the previous week.
| Platform | Oct. 5-11 volume | Week-over-week change |
|---|---|---|
| Kalshi | $19.03 billion | +3.57% |
| Polymarket US | 2.82 billion | +4.25% |
| Polymarket | $498.81 million | −3.89% |
These figures use different reporting methods. Kalshi's headline is $1-face-value contract volume; Polymarket US uses the venue-native Trade Volume field from its Daily Market Reports; and Polymarket uses taker-side cash-dollar volume. Polymarket US's reported quantity is not treated as cash-dollar turnover. The figures should not be added into a combined industry total.
Kalshi reaches the highest total in the six-week series
Kalshi's $19.03 billion in weekly contract volume was its highest total across the six completed weeks reviewed. That figure represents contracts counted at $1 face value, rather than execution-price cash turnover.
Our aggregation recorded $4.42 billion in Kalshi execution-price dollar volume and counted 97.91 million trade executions. The execution count was the highest in the six-week series reviewed. These supporting aggregation measures have not been independently reconciled to the venue's cash-turnover or execution-count series.
Sunday, Oct. 11, was Kalshi's busiest day in our daily aggregation, with $4.20 billion in contract volume and $951.50 million on the supporting execution-price dollar measure. Sunday accounted for 22.09% of the week's contract volume.
Saturday recorded $3.68 billion in contract volume and $767.64 million on the supporting execution-price dollar measure. Together, Saturday and Sunday accounted for 41.44% of Kalshi's weekly contract volume. Activity was stronger over the weekend than on any individual weekday.
Weekend trading and the Polymarket US CAOC subset
Daily trading totals peaked over the weekend, but neither those totals nor unresolved multi-outcome markets provide a verified NFL or college-football breakdown.
Polymarket US's venue-labeled Combinatoric Athletic Outcome Contracts (CAOC) family accounted for a substantial share of reported activity. It is a non-additive subset of the platform's total, not a separate volume total or a verified breakdown of all combos by league.
Polymarket US sees a major Sunday surge
Polymarket US reported 698.83 million in Trade Volume for the Sunday, Oct. 11, Business Date, its busiest reported day of the week.
Reported daily Trade Volume increased from 289.63 million on Wednesday to 404.82 million on Friday and 476.48 million on Saturday before reaching Sunday's peak.
The CAOC-labeled family generated 1.45 billion in reported Trade Volume for the week, representing 51.52% of Polymarket US's total.
On Sunday, CAOC-labeled Trade Volume reached 420.54 million, or 60.18% of the platform's reported daily total. These figures do not allocate combo volume to NFL, college football or other leagues.
Polymarket rebounds over the weekend
Polymarket experienced a midweek slowdown before activity picked up again.
Cash trading fell to $55.94 million on Wednesday, Oct. 7, then recovered to $85.77 million on Saturday and $93.34 million on Sunday.
Despite the weekend rebound, its total weekly cash volume fell 3.89% compared with the previous week.
Kalshi sports and crypto markets remain major contributors
The Sports-labeled subset in our current classification snapshot generated $3.76 billion in contract volume, representing 19.79% of Kalshi's weekly total. It is not a certified all-sports total.
The BTC-labeled subset generated $2.05 billion in contract volume, accounting for 10.78% of Kalshi's weekly total. Other crypto-related labels are listed separately below.
Other mapped labels in the same classification snapshot included:
| Mapped label | Contract volume |
|---|---|
| Finance | $283.99 million |
| Crypto label (BTC/ETH labels separate) | $192.46 million |
| Ethereum | $134.89 million |
| Weather | $27.55 million |
| Midterms | $7.72 million |
| 2028 presidential markets | $6.90 million |
| Trump-related markets | $6.75 million |
| Technology | $6.44 million |
The labels above are selected, mutually exclusive buckets in our current aggregation map, not an exhaustive venue-published taxonomy. Another $12.42 billion, or 65.29% of Kalshi's weekly contract volume, remained unclassified. Current-map reconciliation does not certify historical category coverage or category growth.
Mapped politics and MVP activity
Smaller mapped subsets also contributed to the week's activity. Whole-category week-over-week growth remains unverified because historical classification coverage has not been independently established.
The Politics-labeled subset generated $58.35 million in weekly contract volume.
The MVP-labeled subset generated $5.85 million in weekly contract volume.
Kalshi rises across six reviewed weeks
Across the six completed weeks reviewed, Kalshi weekly contract volume increased from $11.86 billion for the week ending Sept. 6 to $19.03 billion for the week ending Oct. 11, a gain of 60.35%.
Our supporting execution-price dollar measure rose from $3.15 billion to $4.42 billion across the same series. Aggregated trade executions increased from 67.43 million to 97.91 million.
| Week ending | Kalshi contract volume | Kalshi execution-price USD | Polymarket dollar volume | Polymarket US Trade Volume |
|---|---|---|---|---|
| Sept. 6 | $11.86 billion | $3.15 billion | $487.42 million | 974.55 million |
| Sept. 13 | $12.98 billion | $3.21 billion | $540.43 million | 1.66 billion |
| Sept. 20 | $15.27 billion | $3.53 billion | $547.51 million | 2.34 billion |
| Sept. 27 | $15.66 billion | $3.59 billion | $488.42 million | 2.83 billion |
| Oct. 4 | $18.37 billion | $4.44 billion | $519.01 million | 2.71 billion |
| Oct. 11 | $19.03 billion | $4.42 billion | $498.81 million | 2.82 billion |
Kalshi's headline contract volume increased in all five week-over-week comparisons in this six-week series. Its supporting execution-price dollar measure slipped from $4.44 billion to $4.42 billion in the latest week, a 0.50% decline. Growth in face-value contract volume does not necessarily imply growth in execution-price dollar volume.
Polymarket US nearly triples across the six-week series
Polymarket US had the largest relative increase in its own headline-volume measure among the three tracked platforms across the six-week series.
Its reported weekly Trade Volume rose from 974.55 million for the week ending Sept. 6 to 2.82 billion for the week ending Oct. 11, an increase of 189.64%.
The platform's reported weekly Trade Volume peaked at 2.83 billion within this series for the week ending Sept. 27, dipped to 2.71 billion the following week, and then recovered in the latest period.
The timing coincides with the start of the football season and the growth of multi-outcome sports contracts. The data shows these trends occurred alongside the increase, although the weekly totals alone cannot establish how much each factor contributed.
Polymarket remains relatively stable
Polymarket has followed a different pattern. Its weekly cash trading volume remained between $487 million and $548 million throughout the six-week period.
September's total reached approximately $2.17 billion in cash trading. October's total stood at $839.67 million through Oct. 11.
How to read the volume numbers
The three platforms report volume differently, which is important when comparing their size and growth.
Kalshi: The $19.03 billion headline counts contracts at $1 face value. The $4.42 billion execution-price dollar measure and execution counts are supporting aggregation figures, not independently venue-certified cash-turnover or transaction-count series.
Polymarket US: The 2.82 billion figure comes from the venue-native Trade Volume field in official Daily Market Reports. It is kept separate from execution-price cash dollars; the source field alone does not establish a cash-dollar denomination.
Polymarket: The $498.81 million figure measures the dollar value of completed trades, using taker-side executions.
Binary contracts generally trade for less than $1, so their face value can be substantially higher than the amount paid to buy them. For example, buying a contract for $0.40 creates $1 in face-value volume but involves only $0.40 in cash at execution.
The platforms also use different reporting calendars: Kalshi uses UTC weeks, Polymarket US uses official business dates, and Polymarket uses US Eastern time. So the totals are useful for tracking each platform's performance, but they are not directly interchangeable.
What to watch next week
NFL and college football could fuel another active week during Oct. 12-18. Sunday's NFL slate includes the Buffalo Bills at the Las Vegas Raiders and the Dallas Cowboys at the Green Bay Packers. Those games could draw activity in sports and multi-outcome markets, but this remains a forward-looking possibility rather than a quantified forecast.
Economic data releases, including inflation and retail sales reports, could also drive activity in markets tied to Federal Reserve policy and the US economy. Meanwhile, midterm election predictions, Trump's public statements, and ongoing geopolitical developments may create additional trading opportunities.
After Kalshi reached the highest weekly contract-volume total in the six-week series reviewed, the key question is whether another busy weekend can push activity higher.
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