Brennan Center study: Kalshi odds sway voters' expectations of election winners

A new study by the Brennan Center for Justice concludes that odds generated by political event contracts have a measurable influence on how voters judge election outcomes. The research points to the growing visibility of prediction market data, which is now shown to the public through partnerships with outlets including CNN, CNBC and Fox News, often next to or in place of traditional polling figures.

In the experiment, respondents were asked to pick the likely winner in pairs of hypothetical congressional races. Each candidate came with background details such as race, age, party affiliation and previous occupation. Respondents were also shown estimates of each candidate's chances from NBC News polls and from prediction market operator Kalshi. The two sources were randomly varied so researchers could see how people reacted when they disagreed.

The results show that candidates with higher odds on Kalshi were more likely to be seen as the expected winner. A candidate with a 67% chance was 10% more likely to be named the probable winner than one at 50%. When a candidate's odds rose to 84%, the perceived likelihood of winning increased by 20%. Warning voters about the limitations of prediction markets did not reduce their reliance on the odds, according to the study.

The findings come despite widespread scepticism among respondents. Only 19% of voters considered election prediction markets accurate, compared with 37% who said the same of traditional polls. Just 29% believed the markets reflect public opinion accurately, against 55% for conventional polling.

On policy, about 48% of participants favoured stricter regulation of prediction markets, 23% supported banning certain types entirely, and a further 16% said all types should be prohibited. The Brennan Center argues the results suggest tighter regulation may be necessary.

The report arrives as US states move to act on their own. Ohio is preparing legal action against companies including Kalshi and Polymarket, after the Ohio Casino Control Commission issued cease-and-desist notices to them and other firms.