Gamblers Bet $9 Million on US Measles Cases Since January on Prediction Markets

Gamblers have placed nearly $9 million in bets on future measles cases in the United States on prediction markets Kalshi and Polymarket since January 2026, according to @NewScientist reported. These prediction markets allow users to buy and sell shares related to an outcome with yes or no options, where the cost of a bet is determined by others' wagers.

For instance, if 86 percent of wagers on a future event are yes bets, the cost of a yes share is 86 cents, and successful gamblers receive $1 per share if the event occurs.

The concept originated in 1988 when economists Robert Forsythe, George Neumann, and Forrest Nelson at the University of Iowa developed prediction markets to forecast US federal elections. By 2003, infectious disease researcher Philip Polgreen at the University of Iowa incorporated diseases into these markets.

'The original prediction markets were in the spirit of education and public good,' Polgreen stated.

Prediction markets have since become commercial through companies including Kalshi and Polymarket, which are legal in the United States and regulated by the Commodity Futures Trading Commission. In February 2026, a trader using the pseudonym Magamyman won $553,000 on Polymarket by correctly predicting the date of Ayatollah Ali Khamenei's removal from power.

Khamenei was killed on 28 February 2026.

Spencer J. Fox at Northern Arizona University forecasts COVID-19, influenza, and RSV. In June 2025, prediction markets favored an outcome of around 2000 measles cases in the US by the end of 2025. There were actually 2288 measles cases in the US by the end of 2025.

Epidemiologists use multiple data streams including vaccination rates, genomic data, and climate data to predict diseases. 'Measles is a disease that isn’t typically covered by scientific forecasting because it is very probabilistic,' Fox stated. Emile Servan-Schreiber is the CEO of Hypermind, a prediction market company.

'Prediction markets harness the wisdom of crowds, and amateurs bring cognitive diversity that replaces what they lack in expertise,' Servan-Schreiber stated. Kalshi and Polymarket did not respond to New Scientist’s request for comment.