Introducing the "Mamdani Index"

Tracking the 2025 NYC Mayoral Race

Doug Crescenzi

31 Jul 2025 — 5 min read

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TL;DR:

The "Mamdani Index" launches, offering a detailed outlook on Zohran Mamdani’s 2025 NYC Mayoral Election prospects using prediction market data.
Mamdani’s campaign gains traction with a platform emphasizing socialist policies, sparking debates over economic impacts on NYC.
Endorsements from key Democratic figures could play a decisive role in shaping Mamdani’s electoral chances.
The index highlights varying probabilities of Mamdani winning individual boroughs, reflecting regional voter divides.
Elon Musk’s America Party faces challenges in establishing ballot access and fielding candidates for the 2025 cycle.
Political analysts speculate on potential vote splits and market shifts if third-party movements like the America Party gain momentum.

Market Snapshots

Event Breakdown

Tracking the 2025 NYC Mayoral Race: Our newly released "Mamdani Index" offers a comprehensive snapshot of Zohran Mamdani's prospects in the 2025 NYC Mayoral Election, aggregating data from Polymarket and Kalshi prediction markets.

Framed as a radical left figure, Zohran Mamdani’s rise centers upon his campaign doubling down on socialist policies, drawing comparisons to chaotic "Joker politics." His platform—featuring rent freezes, punitive taxes, and expansive housing plans—has fueled support among young progressives but raised concerns about economic fallout, including a potential exodus of wealth from NYC. This aligns with the index’s broader implications: a victory could pressure real estate values and municipal bonds, while defeat might stabilize markets. Mamdani’s campaign symbolizes a global trend of left-wing escalation and potentially foreshadows a rise in socialism across the United States.

This week, the index sits at 45.3%, with the probability of Mamdani winning the election standing at 79% on Polymarket. His odds of securing over 50% of the vote hover around 48%, reflecting a competitive race.

Borough-level forecasts show varied strength: 67% chance of winning The Bronx, 95% for Brooklyn, 86% for Manhattan, 72% for Queens, and a lower 18% for Staten Island where the last Democrat to win was Ed Koch in 1985.

The index also tracks borough wins, with 23% probability for three boroughs, 56% for four, and 13% for all five. This granularity helps investors gauge regional impacts—Brooklyn and Manhattan’s higher odds contrast with Staten Island’s resistance. Bill de Blasio was the last candidate to win all 5 boroughs in the 2013 NYC mayoral election.

Endorsements play a pivotal role in Mamdani’s path to victory. The likelihood of Barack Obama backing Mamdani sits at 9% on Polymarket and 10% on Kalshi, while Kamala Harris’s support is pegged at 12% and 10% respectively. Kathy Hochul’s endorsement odds are 37% (Polymarket) and 37% (Kalshi), and Chuck Schumer’s stands at 30% on Kalshi. These figures indicate a cautious but potentially influential alignment from Democratic heavyweights, though shifts could reshape the index.

Mamdani’s campaign narrative blends ideological zeal with practical challenges. Fund managers may closely monitor the Mamdani Index as it provides a forward-looking gauge of political and economic shifts that could impact NYC-centric investments. A trend toward victory, with odds like 79% on Polymarket, signals potential policy changes—such as rent controls or tax hikes—that could depress real estate values, municipal bond yields, and REIT performance, while driving capital flight to states like Florida. Conversely, a defeat trend might stabilize these assets.

Prediction market-driven indexes, like the Mamdani Index, offer a data-rich, probabilistic lens that empowers stakeholders to anticipate and navigate the economic and political currents shaping our future. By leveraging the index’s dynamic data managers can adjust portfolios in real-time, ensuring agility in a fluid market landscape.

Related markets & forecasts:

Long-Tail Radar

The "Long-tail Radar" this week zeroes in on Elon Musk’s America Party, spotlighting three intriguing Polymarket markets that reflect its nascent political gamble. The first, "America Party candidate on a federal or gubernatorial ballot in 2025?" ($15,133 volume), tracks the party’s uphill battle for ballot access, with odds plummeting from 50% to a steady 10% by July 31, 2025, signaling legal and logistical hurdles. The second, "America Party wins a federal or gubernatorial election in 2025?" ($28,708 volume), mirrors this decline, dropping from 30% to under 10%, underscoring the long odds of electoral success given the party’s embryonic status. The third, "Congressman joins the America Party before August?" ($34,153 volume), shows a continuous decline to less than 1%, hinting at unlikelihood as the deadline looms.

These markets captivate due to Musk’s polarizing influence and the party’s fiscal conservative pitch, which could disrupt traditional alignments. The chart reveals a sharp early enthusiasm fading into skepticism, aligning with reports of uncompleted FEC registration and ballot qualification efforts. If the America Party gains traction—say, winning a Congressional or Senate seat—markets could see volatility. Real estate and municipal bonds in affected districts might dip as Musk’s anti-spending stance rattles local economies, while gold or defensive stocks could rise amid uncertainty. A GOP vote split might bolster Democrats in tight races, pressuring Republican-led sectors. With $77,994 in combined volume, these markets offer a real-time pulse on a third-party experiment, making them an interesting watch for investors navigating this political wildcard.

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