Kalshi accepted more than $120 million in contract sales and purchases during Zohran Mamdani’s successful New York City mayoral campaign.
Users at Kalshi had Mamdani down for at least a 90% chance to win the election at every point over the last 24 hours.
Key Takeaways
- Kalshi’s New York users believed that Cuomo would win the race as of Monday.
- One user purchased a $2.9-million contract on Mamdani.
- Four of the five boroughs voted for Mamdani.
Money was flying into Kalshi even during the waning hours of the election. The prediction platform reported more than $30 million in trading volume after noon Eastern on the day of the NYC Mayoral election.
One user even purchased a $2.9-million contract at a 92% chance for Mamdani to win, netting $249,628.
BREAKING: A trader has a $2.8M position on Zohran Mamdani winning the NYC Mayor Election pic.twitter.com/IOJ6jBLv2N
— Kalshi (@Kalshi) November 4, 2025
Mamdani, 34, was declared the projected winner of the race with 50.4% of the votes. He beat Independent Andrew Cuomo (41.6% of votes), whom he also defeated in the summer’s Democratic primary, and Republican Curtis Sliwa (7.1% of votes).
BREAKING: Zohran Mamdani references his Kalshi odds on stage
— Kalshi (@Kalshi) October 27, 2025
Kalshi is mainstream. pic.twitter.com/hLCzqLL7G2
Four of New York City’s five boroughs – The Bronx, Brooklyn, Manhattan, and Queens – all voted in favor of the Democrat. Only Staten Island favored Cuomo (55.4%) and gave Mamdani and Sliwa near-even shares of votes (22.7% to 21.3%).
According to exit poll data shared by NBC News, 50% of male and 50% of female voters wrote Mamdani’s name on their ballot. He did the best with minority communities but still got 46% support from White voters, ahead of Cuomo (45%) and Sliwa (8%).
The biggest disparity in voting demographics came in age, as 78% of voters aged 18-29 and 66% of voters aged 30-44 voted for Mamdani. Only 17% and 28% were for Cuomo, in those respective demos.
Conversely, Cuomo won the vote with the 45-64 and 65+ groups. He received 47% and 56% of the votes in those groups, respectively, while Mamdani claimed 43% and 36%.
Polymarket reports huge numbers
Polymarket reported a staggering $429.6 million in contracts related to the NYC Mayoral race.
According to their site, $143.3 million was spent purchasing contracts for Mamdani to win the election. Sliwa received $60.4 million, and Cuomo claimed $48.8 million. Polymarket had given Mamdani better than an 80% chance to win the election since August.
One trader spent nearly $40,000 on a contract that required Mamdani to receive at least 50% of the general vote, and more than $60,000 on another that said he would win the election.
A Polymarket trader @fengdubixuying just dumped $103,408 into exactly two bets: $39,537 that Mamdani gets 50%+ in the general, and $63,871 that he wins NYC mayor. Zero spread, zero curiosity.
— Polymarket Whales (@PolyWhaleWatch) November 5, 2025
Either @fengdubixuying knows the exit polls or is Mamdani’s bookie. pic.twitter.com/Jm2c9YYdS3
Kalshi NYC users were wrong
Despite Kalshi users’ strong belief that Mamdani would become New York City’s next mayor, local traders weren’t as bullish.
Kalshi shared the day before the election that traders in two boroughs favored Mamdani, two favored Cuomo, and one, The Bronx, was split evenly at 36%.
Users who purchased contracts for Mamdani to win the election were also much younger on average, which matches the exit poll data. They also risked less money, reporting significantly lower mean ($1,537) and median ($29) trading positions than Cuomo ($1,625 and $200) and Sliwa ($3,920 and $467).
All in all, NYC traders were higher on Cuomo (49%) than they were on Mamdani (40%) as of Monday. Out-of-state users were higher on Mamdani, 58-33%.
