Why prediction markets swung heavily toward Harris before Election Day

Polymarket odds on the presidential election winner.

Former President Trump chances of regaining the White house fell over the weekend across prediction markets like Polymarket and Kalshi.

Volatility like underlines why using betting markets to gauge status of presidential race is tricky.

Prediction and betting markets have emerged this year as force in shaping public opinion campaign messaging about horse race.

The big picture

Prediction markets are misnamed.

They are betting lines intended to provide price to wager on at given moment in time not necessity to predict whether the outcome is probable.

The public judge success of prediction market based on result of election with trump victory meaning markets were right along while Harris win means they messed up.

Trump chance of regaining the White House fell from 67% on Polymarket on Oct 30 to 53% on Sunday back to 62% on Tuesday morning.

VP Harris move from 33% to 47% to 38%.

Hillary Clinton odds of winning in 2016 on PredictIt were 82% the day before Election Day.

Bookies put 90% odds on UK voters rejecting Brexit.

Prediction markets political polls are measure of current emotion and not predictive.

Single individual can sway prediction markets with big bets as Axios Brady Dale last month.