Backing Polymarket’s primary favorites would have lost 4%, new audit finds.
Key Summary
A hypothetical strategy of backing the favorite on prediction market Polymarket in every scored 2026 US primary would have lost 4%, despite those candidates winning 87% of the time, according to a blockchain data provider's scorecard. This analysis separates the questions of who is most likely to win and whether their contract is worth the price. The study found that candidates priced at 90 cents or more won 177 of 182 races, but the outcome share pays $1 when it wins and nothing when it loses, making expensive favorites unprofitable on a winning share.
Backing Polymarket Favorites Lost 4% in 2026 US Primary Elections
Study Overview
A blockchain data provider, Bitquery, conducted a study on the hypothetical strategy of backing the favorite on prediction market Polymarket in every scored 2026 US primary. The study found that this strategy would have lost 4%, despite those candidates winning 87% of the time.
Results
The candidate with the highest study reference price won 238 of 273 Senate, House, and governor primaries. However, the hypothetical strategy of putting $1 on each favorite at the study's reference price lost four cents per dollar. Related Reading Most world cup traders won less than $5 on Polymarket while FIVE wallets walked away with millions.
Analysis
The strongest favorites did much of the work behind the headline accuracy rate. Candidates priced at 90 cents or more won 177 of 182 races. Among favorites priced between 50 and 90 cents, however, 71% won despite an average price of 77 cents. An outcome share pays $1 when it wins and nothing when it loses. Buying an expensive favorite therefore leaves little profit on a winning share, while a losing share wipes out its purchase cost.
Limitations
Bitquery averaged trades during the 24 hours before 12:00 UTC on voting day. When a candidate had no trade in that window, it used the last trade within the preceding 30 days. For races that went to a runoff, it used the runoff date. Those averages, and potentially stale fallback trades, are reference prices rather than guaranteed buy quotes at the cutoff. The published methodology does not specify a full adjustment for spreads, slippage or fees. Polymarket’s current fee page lists a politics fee range of 0% to 1%, but does not establish the charges on the historical trades in this sample.
Conclusion
The study excluded nine markets because some settled before voting, some lacked usable prices and one lacked a settlement record. It covered primaries in the 50 states using Polygon trade data, leaving out Polymarket’s US app and other venues such as Kalshi. For November’s prediction markets, the distinction between forecasting and pricing remains useful. The measured primary record itself may not carry over: Bitquery cautions that general elections attract more money and polling than small, local contests.