Favorite-Longshot Bias
Favorite-longshot bias is the empirical tendency for participants to overprice unlikely outcomes (longshots) and underprice likely ones (favorites), so longshots are systematically overbet relative to how often they actually win.
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Explained Simply
First documented in horse-race betting, the pattern shows up across many wager-style markets: low-priced 'longshot' contracts win less often than their price implies, while high-priced 'favorite' contracts win slightly more often than theirs. The practical result is that blindly buying cheap longshots tends to produce negative average returns, while favorites are comparatively better value. A CEPR study of the Kalshi prediction market (Bürgi, Deng & Whelan, 2025), using more than 300,000 contracts, found the same favorite-longshot pattern — low-price contracts won far less often than needed to break even after fees, and the effect was more pronounced for takers than makers.
Why Longshots Get Overbet
Several explanations are proposed. Some bettors are risk-loving and enjoy the lottery-like payoff of a cheap contract that could multiply. Others simply overestimate small probabilities, treating a 5% event as if it were 10%. On maker-driven venues, more pricing margin also tends to be loaded onto the longshot end of the market.
Whatever the mix of causes, the observable effect is consistent: the cheapest contracts, as a group, underperform what their prices imply.
What It Means for Prediction-Market Traders
The bias suggests caution around low-priced 'lottery ticket' contracts, which historically win less often than their price implies. Favorites can be relatively better value, but they offer small reward per contract and still carry risk.
Importantly, this is a documented tendency, not a guaranteed strategy. Fees, position limits, variance, and the small chance of a surprise outcome can erase any theoretical edge, so treat it as context rather than a trading system.
Frequently Asked Questions
What is favorite-longshot bias in simple terms?
It is the tendency for people to bet too much on unlikely outcomes and too little on likely ones, so longshots are priced higher than their true odds while favorites are priced a bit low.
Does favorite-longshot bias appear in prediction markets like Kalshi?
Yes. A 2025 CEPR study (Bürgi, Deng & Whelan) of over 300,000 Kalshi contracts documented a clear favorite-longshot pattern: cheap low-price contracts won far less often than needed to break even after fees, more so for takers than makers.
Can I profit from favorite-longshot bias?
The bias describes a historical pricing tendency, not a guaranteed edge. Fees, limits, variance, and surprise outcomes can wipe out any theoretical advantage, so this is educational context rather than financial advice.
How Tradewink Uses Favorite-Longshot Bias
Tradewink Predictions looks for markets where a contract's price diverges from our calibrated probability estimate — for example, cheap longshots that may be overpriced. We frame this as educational analysis of pricing patterns, not a signal to place any trade or a claim of edge.
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See Favorite-Longshot Bias in real trade signals
Tradewink uses favorite-longshot bias as part of its AI signal pipeline. Get daily trade ideas with full analysis — free to start.