Prediction Markets Put Eric Adams' NYC Mayoral Bid at 50-50 After 'Dummy Ballot' Snafu

Prediction markets are signaling that front-runner Eric Adams' chances of becoming the next mayor of New York City have dropped to around 50% following a vote-counting snafu in the Democratic primary.

On PredictIt, perhaps the best-known prediction market, the price to bet on an Adams victory had dropped to 53 cents from 89 cents in the last 24 hours as of midday Eastern time.

The contract settles at $1, so the price indicates the market now thinks the retired police officer and Brooklyn borough president has a 53% probability of running the largest U.S. city.

Meanwhile, on Polymarket, a decentralized prediction market build on Ethereum sidechain Polygon, betting on an Adams win in the Democratic primary has slipped to 43 cents from 81 cents over the same 24-hour period.

The change in market signals reflects confusion and uncertainty after the city Board of Elections rescinded a tally of primary votes on Tuesday, citing an unspecified "discrepancy." The board later said it had included 135,000 "dummy ballots" in the count.

This is the first time in decades the city has used ranked-choice voting, in which New Yorkers may vote for multiple candidates, ranked by preference, rather than just one.

How prediction markets work

In prediction markets, investors bet on the outcomes of real-world events, from elections to sports matches.

Proponents tout these markets as a way to induce experts to express what they really think will happen, since there is money on the line, at a time when public trust in pundits and other authorities is eroding.

Whoever wins the Democratic primary will face Republican nominee Curtis Sliwa, best known for leading the 1980s vigilante group Guardian Angels, in the general election on Nov. 2.

On PredictIt, Sliwa shares are trading at 3 cents, speaking to New York's strongly Democratic voter advantage. Former Sanitation Department official Kathryn Garcia is trading at 46 cents.

UPDATE (May 30, 15:60 UTC): Corrects figure in third paragraph, adds links throughout.