Glossary
Implied probability
The chance a YES share price encodes: on Polymarket, 34¢ last is read as 34%. It is a quote, not a forecast.
On Polymarket a YES share is a claim on $1 if the listed outcome happens and $0 if it does not. That is why a 34¢ last trade is read as 34% implied probability: you paid 34 cents for a dollar that pays only if YES wins. NO is the complement on a healthy book — roughly 66¢ when YES is 34¢ — minus the spread between the two sides.
Implied probability is a quote, not a model output. A thin 15-minute crypto book, a NegRisk cluster with leftover dust, or a whale walking the ladder can all move the number without anyone “updating a forecast.” Sportsbooks also quote implied probability, but they bake in vig so the two sides sum to more than 100%. Polymarket’s complete set (YES + NO) is designed to mint and merge against $1 of collateral, so the two prices should hug 100% plus or minus the spread, not a bookmaker overround.
Treat the percent as a unit conversion. Turn ¢ into percent, American moneyline, or decimal odds with the odds converter; size a hypothetical win with the payout calculator. Then look at volume, depth, and who actually traded — the headline percent does not tell you if the print is real. Polydata never executes trades; the converters are research arithmetic, not tickets.