NFL, tennis and the Fed lift prediction markets to $14.1 billion

Global prediction markets picked up sharply in the week of Sept. 7-13, helped by the start of the NFL regular season, a cluster of U.S. Open matches, esports playoff series and continued interest in the Federal Reserve’s upcoming rate decision. Combined contract volume across Kalshi and Polymarket Global rose 9.3% from the previous week to $14.10 billion, while the total number of trades increased 10.7% to 86.5 million.

As reported on Sept. 13, NBC News said the NFL season could be prediction markets’ biggest yet, and Kalshi was the clear leader in the weekly totals. Kalshi recorded $12.98 billion in contract volume, or 92.1% of the combined market, while Polymarket Global rose 7.6% to $1.11 billion and held 7.9%. Polymarket US reported $818.5 million across five daily reports, and open interest stood at 677.2 million contracts on Kalshi, 321.3 million on Polymarket Global and 164.2 million on Polymarket US.

Sports contracts were the biggest source of retail trading activity on prediction market apps during the week. Kalshi and Polymarket Global together generated $3.76 billion in sports contract volume, with Kalshi accounting for $3.265 billion, up 2.2%, and Polymarket Global at $498.8 million, up 104.7%. Polymarket US added $406.6 million in sports volume across its five posted daily reports.

The biggest sports market on Kalshi was New England Patriots vs. Seattle Seahawks, which generated $57.86 million in contract volume. Ohio State vs. Texas followed at $51.91 million, then San Francisco 49ers vs. Los Angeles Rams at $45.3 million. SMU vs. Florida State drew $39.85 million, while Washington vs. Philadelphia and Green Bay vs. Minnesota also ranked among the week’s larger football markets.

Tennis activity climbed as the U.S. Open reached its final stages. Ben Shelton vs. Carlos Alcaraz generated $40.36 million on Kalshi, $13.02 million on Polymarket US and $7.01 million on Polymarket Global. Frances Tiafoe vs. Alex Michelsen drew another $35.83 million on Kalshi, along with $9.09 million on Polymarket US and $7.01 million on Polymarket Global.

Outside sports, Polymarket Global’s “Fed Decision in September?” market was the biggest non-sports market across the industry, generating $48.85 million in volume, up 48.8% from the previous week. The report said traders were positioning ahead of the Federal Open Market Committee meeting, and that interest-rate markets attracted more liquidity on Polymarket Global.

Esports also contributed to the weekly jump. On Polymarket Global, four esports markets generated more than $38.74 million in combined weekly volume, led by Hanwha Life Esports vs. T1 at $10.84 million and Gen.G vs. Hanwha Life Esports at $10.79 million. In China’s LPL playoffs, Anyone’s Legend vs. Invictus Gaming brought in $10.17 million, while Bilibili Gaming vs. Anyone’s Legend added $6.94 million.

The broader trend favored Kalshi over the past six weeks. From Aug. 9 through Sept. 13, its weekly volume rose for five consecutive weeks and was up 60.9%, while its share of the combined market climbed from 88.0% in late August to 92.1%. Polymarket Global, by contrast, had fallen for two straight weeks before rebounding in the Sept. 7-13 period, and its average completed week in September was $1.114 billion, almost exactly in line with its August average of $1.116 billion.