The opening week of the 2026 NFL season delivered a sharp increase in prediction market activity, with Kalshi setting consecutive daily volume records and several competing platforms reaching their own milestones.

Kalshi recorded $2.426 billion in total volume on Saturday before edging past that figure with $2.433 billion on Sunday. Multi-leg contracts contributed heavily to both records, while football generated hundreds of millions of dollars in additional activity.

The wider prediction market sector also experienced significant growth during the week of September 7-13. Combined contract volume across Kalshi and Polymarket Global reached $14.10 billion, rising 9.3% from $12.90 billion during the previous week. The two platforms recorded 86.50 million trades over the period.

Kalshi accounted for $12.98 billion of that weekly volume, an increase of 9.4%, giving the exchange 92.1% of the combined total. Polymarket Global generated $1.11 billion, up 7.6%.

Football Drives Record Weekend Activity

NFL markets played a central role in the weekend increase. Kalshi recorded $388.1 million in NFL trading volume on Sunday when combo markets were excluded, representing 76% of the $510.9 million reported across seven operators.

From the Wednesday season opener through Sunday, more than $617 million in NFL markets traded on Kalshi. Football activity also contributed to the exchange’s record overall totals across the weekend.

Straight football contracts generated $328.7 million on Saturday and $409.9 million on Sunday. Multi-leg contracts were considerably larger, producing approximately $1.47 billion on Saturday and $1.48 billion the following day.

Kalshi’s largest individual market of the weekend involved the Sunday Night Football matchup between the Dallas Cowboys and New York Giants. The game-winner market recorded $56.3 million in volume, while another $16.3 million went through the spread market. Saturday’s Ohio State-Texas college football matchup generated $52.1 million.

Across the wider September 7-13 period, sports contract volume on Kalshi and Polymarket Global reached $3.76 billion. Kalshi contributed $3.265 billion, while Polymarket Global’s sports activity climbed 104.7% to $498.81 million.

Football also helped other prediction exchanges establish new highs. DraftKings Predictions recorded its first $100 million trading day on Saturday, then increased that record to $139.8 million on Sunday. Sports and combo markets contributed $98 million to Sunday’s total.

Crypto.com exceeded $100 million in daily volume for the first time on Sunday. Novig reached $66.1 million on Saturday and followed with $69.1 million on Sunday. ProphetX surpassed $10 million on consecutive days for the first time.

Combo Markets Account for Much of the Volume

Multi-leg markets represented more than half of Kalshi’s total activity on both record-setting days. Across reported operators, combo trading reached $1.69 billion on Sunday alone, with Kalshi responsible for $1.49 billion.

Weekly figures also showed the growing size of these contracts. Kalshi’s non-additive combo volume increased 11.1% to $1.93 billion, giving the platform 99.4% of the combined $1.95 billion combo market measured alongside Polymarket Global.

One five-part contract tied to NFL player rushing or receiving performances generated $36.44 million in volume during the week.

The structure of prediction market volume makes direct comparisons with traditional sportsbook handle difficult. Kalshi includes funds from both the taker and maker sides of a trade when calculating volume. Market makers can account for a particularly large proportion of reported activity in long-odds combo markets, InGame reports.

Kalshi’s taker-side volume reached $555.7 million on Saturday and $596.7 million on Sunday. Both figures remained below the exchange’s $640.3 million record set on July 11.

Fees came close to previous highs as well. Kalshi generated $15.99 million in fees on Saturday and $16.02 million on Sunday, for a combined total of more than $32 million. Its July 11 record stands at $17.1 million for a single day.

Takers lost $2.1 million before fees on Sunday and $15.2 million after fees. On parlays, taker losses stood at $200,000 before fees and $4.1 million after fees.

Kalshi Extends Its Recent Growth Run

The NFL opening weekend added to several weeks of rising activity for Kalshi. Weekly volume increased from $8.069 billion for the week ending August 9 to $12.983 billion for the week ending September 13. Across that six-week period, volume rose 60.9%.

Through September 13, Kalshi had generated $23.45 billion in month-to-date contract volume, 53.4% above the comparable August period.

Polymarket also recorded substantial Sunday activity. Jefferies estimated that the platform generated approximately $404 million in volume during the day. With Polymarket included, total prediction market volume across tracked operators was expected to move comfortably above $3 billion on Sunday.

Analysts from Citizens also compared Kalshi’s pricing with major sportsbooks during NFL Week 1.

“Kalshi pricing was better than DraftKings and FanDuel in Week 1,” analysts Jordan Bender and Isabelle Slavin wrote. “We tracked odds and implied vig (operator pricing) across the Week 1 NFL slate for FanDuel, DraftKings, and Kalshi, covering moneyline bets and over/under (28 data points). We tracked pre-game pricing on Friday (9/11) afternoon, with Kalshi offering 3% lower implied vig than FanDuel and 4% lower than DraftKings across these games.

The comparison produced a different result for combo markets. Bender and Slavin calculated Kalshi’s implied vig at 23.8%, compared with 22.0% at DraftKings and FanDuel before transaction fees.

The weekend also produced an unusually large three-leg parlay involving the Cowboys, Las Vegas Raiders and Philadelphia Eagles. Two block trades on the contract carried a combined value of $3.7 million, with the taker contributing exactly $1 million. It marked the largest amount placed on the “yes” side of a parlay in Kalshi’s history. The contract ultimately lost after the Giants defeated the Cowboys following successful results on its first two legs.