Share 
Kalshi and Polymarket set the pace for NFL Week 1 prediction market activity, with the two operators combining for more than $1 billion in NFL trading over the first six days of the season, according to figures cited by iGaming Business.
Kalshi alone posted $983.4 million in NFL volume, based on DeFi Rate data referenced by the source. The same report said overall prediction market volume for the week reached a record $15.9 billion, up 16% from the previous week.
Kalshi remained dominant, but its share slipped
Even with the strongest reported NFL volume, Kalshi’s market share fell to 82% for the week ended 13 September, down from 86% a week earlier. The source said Kalshi still held a roughly nine-fold lead over Polymarket, its nearest rival.
Bank of America analyst Shaun Kelley said Kalshi may have been "over indexing" on college sports when discussing the platform’s Sunday volume pattern.
The week closed after the Chiefs beat the Broncos 31-10 on Monday Night Football, a result the source tied to what it described as the biggest week yet for prediction markets.
Polymarket led app downloads as rivals also gained
While Kalshi led reported NFL trading volume, Polymarket topped app downloads with 762,000, according to a company statement cited by the source. That represented a 13,509% weekly increase and 25% of total category downloads.
Other operators also posted gains. DraftKings and Underdog recorded weekly growth of 125% and 119%, respectively. The source also said Polymarket, Crypto.com and Novig each gained at least 30% week over week, with Polymarket up 46%.
Crypto.com recorded $350 million in weekly trading volume, according to The PM Pulse, and four operators reached at least $300 million in activity.
What to watch in Week 2
The source said upcoming NFL primetime matchups could keep prediction market activity elevated. As of Wednesday afternoon, Kalshi showed the Rams with a 75% probability of beating the Giants on Monday Night Football.
The article also noted Robinhood’s minority stake in Crypto.com and a deal to route NFL contracts to OG.com, a regulated prediction market platform. How much that arrangement affects future volume was not yet clear from the reporting.
For players and market watchers, the main takeaway is that NFL demand is expanding beyond a single operator, even as Kalshi remains the clear volume leader.
—
Source: As reported by igamingbusiness.com.
