Table of Contents

• You might want to know


• Main Topic


• Key Insights Table


• Afterwards...

You might want to know

Which Mamdani-backed candidates do prediction markets expect to win, and how do those odds compare across the city’s competitive congressional primaries?

Main Topic

On a recent Tuesday evening, New York City Mayor Zohran Mamdani faced his first substantial test of influence since taking office in November 2025. While Mamdani himself was not a candidate on the ballot, his endorsements carried weight in several tight Democratic congressional primaries across the city. He publicly supported three contenders: former New York City Comptroller Brad Lander in New York’s 10th Congressional District, state Assemblymember Claire Valdez in the 7th District, and first-time candidate Darializa Avila Chevalier in the 13th District. Prediction market activity — particularly on the Kalshi platform — suggests markets expect Mamdani to see mixed success with those endorsements.

Kalshi traders collectively priced the likelihood that Valdez and Lander would win their nominations while Chevalier would fall short at about 54%. Markets also assigned a 28% chance that all three endorsed candidates would prevail, and a 20% probability that only Lander would succeed. These probabilities come from combination contracts on Kalshi, which resolve to “yes” only if each specified outcome — a win or a loss for every named candidate — actually occurs. The final outcomes for these combo contracts are verified against official results published by the New York State Board of Elections.

It’s important to note that prediction market prices reflect traders’ aggregated beliefs and incentives, not the same methodology used in conventional political polling. As such, market odds provide a different lens on electoral expectations but are not a direct substitute for opinion surveys or demographic analysis.

Looking at each race individually: In the 10th District, Brad Lander — a Mamdani ally — is running against incumbent Democratic Rep. Dan Goldman. Goldman has faced criticism from some on the left for his support of Israel; the district includes downtown Manhattan and Park Slope in Brooklyn. On Kalshi’s contract asking whether a candidate will secure the Democratic nomination in the 10th, traders priced Lander with a near-certain probability of winning the party’s nomination, reflecting strong market confidence in his chances. Kalshi verifies individual nominee contract outcomes with the Democratic Party’s official results.

In the 7th District contest to replace retiring Rep. Nydia Velázquez, Claire Valdez is challenging a field that includes Brooklyn Borough President Antonio Reynoso, who received Velázquez’s endorsement. The race maps across Williamsburg in Brooklyn and Long Island City in Queens; politically, Reynoso has backing from the progressive Working Families Party, whereas Valdez has support from the Democratic Socialists of America. Market participants on Kalshi favored Valdez in that contest, giving her roughly a 80% chance of clinching the Democratic nomination.

The 13th District primary features Darializa Avila Chevalier — also backed by the Democratic Socialists of America — mounting a challenge to incumbent Rep. Adriano Espaillat, who chairs the Congressional Hispanic Caucus. The 13th covers Harlem and Washington Heights in Manhattan and parts of the Bronx. Kalshi traders gave Espaillat about a 66% chance of fending off Chevalier’s challenge, indicating markets saw Chevalier as the underdog in that matchup.

Separately, another hotly contested primary is underway in New York’s 12th District, which spans midtown Manhattan, the Upper East Side and the Upper West Side. Mamdani did not make an endorsement in that race. The 12th has attracted significant outside spending tied to debates over artificial intelligence policy: Super PACs aligned with rival AI industry interests have intervened to shape the race. Alex Bores, a state Assemblyman and vocal supporter of AI regulation, has drawn opposition spending from an OpenAI-backed group called Leading the Future, which has spent roughly $8 million against him. At the same time, an Anthropic-backed group, Public First Action, has spent about $11 million supporting Bores. Despite that high-profile spending dynamic, Kalshi traders currently favored fellow state Assemblymember Micah Lasher in the 12th, pricing his chance of winning the Democratic nomination at around 74%.

These market probabilities reflect aggregated trader expectations at a given point in time and can shift as new information emerges, such as late endorsements, campaign spending reports, debates, or local developments. They also highlight how influential endorsements — like Mamdani’s — can be in shaping perceptions of viability, while not guaranteeing outcomes when entrenched incumbents, competing progressive coalitions, or significant outside spending are in play.

Finally, there is a commercial relationship to disclose: CNBC and Kalshi maintain a business connection that includes customer acquisition and a minority investment, which users should consider when evaluating coverage that cites Kalshi market data.

Key Insights Table

Afterwards...

Looking ahead, these markets will continue to update as campaigns progress, ballots are cast, and official results are tallied. Endorsements like Mamdani’s can move perceptions and mobilize specific voter blocs, but incumbency advantages, intra-progressive rivalries, and large-scale outside spending remain powerful forces. Observers should watch late-campaign developments, late-breaking endorsements, fundraising and ad spending, and any shifts in voter sentiment reflected by both polls and market prices. Ultimately, combining multiple information sources — polls, market odds, ground reporting, and official filings — will provide the most complete view of how these primaries are likely to resolve.