This November’s midterm election will see 36 Gubernatorial races and 35 U.S. Senate races. Of the 44 states with at least one of those elections, 26 states will hold both.
PredictIt currently has a market for 17 Senate races and 17 Gubernatorial races, but only one state has traders splitting their proverbial ticket: Pennsylvania.
Traders are giving an ever so slight edge to Republicans (likely to be Dr. Oz) in the Senate race while strongly favoring Democrat (and current state Attorney General) Josh Shapiro in the Gubernatorial race.
To find the implied probability of Pennsylvania Senate and Gubernatorial PredictIt share prices, we used the following formula:
(bestBuyYesCost + (1-bestBuyNoCost) + BestSellYesCost + (1- BestSellNoCost)) / 4
| Candidate | Senate “Yes” price | Governor “Yes” price |
| Republican | 0.515 | 0.405 |
| Democratic | 0.505 | 0.625 |
Republicans were the strong favorite in both races until the May 17th primary.
While Republican and Democrat Senate shares have converged around 0.50/share, with Republican (Dr. Oz) shares narrowly ahead now, Gubernatorial shares essentially flipped from where they were in April.
In a heavily polarized electorate, it’s becoming increasingly rare to see voters cast a split ticket. Three states in 2020 split their Gubernatorial and Presidential ballot: New Hampshire, Vermont, and North Carolina. Only Maine split its Senate and Presidential ballot, voting for Susan Collins and Joe Biden.
Prediction market traders buy and sell binary option contracts: an event either happens or does not happen (Yes or No). A correct prediction receives $1/share, and a wrong prediction receives $0/share. The market prices can indicate what traders believe is the probability of the event happening.
PredictIt is a prediction market run by Victoria University of Wellington, New Zealand, and Aristotle International, Inc. PredictIt limits both investment amounts and the number of investors per market. Participation is limited to individuals 18 years of age or older who are U.S. Persons. There are no controls on insider information.