TLDR
- A Brennan Center study says election prediction market odds affect voters about as much as traditional polls.
- Voters were 10 to 20 percentage points more likely to believe a market favorite would win, regardless of polls.
- Only 20% of respondents view prediction markets as accurate.
- More than 80% want political event contracts more tightly regulated or banned outright.
- The findings come about two weeks before Election Day.
Election prediction markets are shaping how American voters view candidates, according to a new study from the Brennan Center for Justice. The findings were released with Election Day about two weeks away.
The study found that prediction market odds affect voter opinions in a way similar to traditional polls. It also found that most voters want these markets to face tighter rules.
More than 80% of respondents said political event contracts should be more tightly regulated or banned outright.
How Prediction Markets Differ From Polls
The Brennan Center said many voters do not understand how prediction market odds differ from poll results. The two are often shown side by side in news coverage.
“Election prediction market odds are often shown alongside, or even in place of, traditional polling numbers, but they are produced very differently,” the Brennan Center said.
A poll asks a sample of voters who they plan to support. That sample is meant to represent the wider electorate.
Prediction market odds work differently. They are based on the prices at which traders buy and sell contracts tied to a specific outcome.
These concerns come as more yes/no exchanges form partnerships with traditional media outlets. Those include online, print and television sources that many Americans use for political news.
Voters Swayed by Market Favorites
Few respondents trust prediction markets. Only 20% said they view these markets as accurate, and about one third said election contracts reflect the views of the broader public.
Even so, the markets still influenced how voters judged a race. “If a candidate was favored by prediction markets, voters were between 10 and 20 percentage points more likely to believe that the candidate would win, regardless of what the polls said,” the study found.
The effect also worked in the other direction. Voters were 11 percentage points less likely to say a candidate with 33% odds would win.
That gap grew to 19 percentage points for a candidate with 16% odds.
The Brennan Center said prediction market odds had an effect on perceived electability similar to polls. That effect was stronger than any of the candidates’ background traits, including demographics, occupation or past experience.
Some observers have raised concerns that polls can act as a form of voter suppression. The argument is that showing one candidate far ahead may lead the other candidate’s supporters to stay home.
Prediction markets have correctly called some major races. They pointed to the right winner in the 2024 presidential election.
Major exchanges also showed Zohran Mamdani as the clear favorite ahead of the 2025 New York City mayoral election, which he went on to win.
The study also asked voters what should happen next. Twenty-three percent said some parts of prediction markets should be halted, while 16% said the industry should be banned completely.
Voters head to the polls for the midterm elections on November 3.
