How to read prediction-market odds

Prediction-market odds look intimidating until you learn the one rule that unlocks all of them: the price in cents is the implied probability in percent. A Yes share trading at 62¢ implies a 62% chance; a share at 7¢ implies 7%. Everything else in this guide is refinement on that rule.

From price to probability — and payout

Shares settle at $1 if the outcome occurs and $0 if it does not, so the price is what the market collectively pays today for a $1 claim on the event. Three numbers follow directly from it:

• Implied probability: the price itself. 62¢ → 62%.
• Potential return: (100¢ − price) ÷ price. At 62¢, a winning Yes returns 38¢ on 62¢ risked — about 61%.
• Your edge: your probability minus the market’s. If you believe the true chance is 70% and the price is 62¢, your expected value is 0.70 × $1 − $0.62 = 8¢ per share. No edge, no trade.

Bid, ask, and the real price of trading

A live market has two prices: the bid (the most a buyer currently offers) and the ask (the least a seller accepts). If Yes is bid 61¢ / ask 63¢, the “price” you see quoted is usually the last trade or the midpoint (62¢), but you buy at 63¢ and sell at 61¢. The gap is the spread:

• A tight spread (a cent or two) means an actively traded market whose price you can take mostly at face value.
• A wide spread (five cents or more) means the “implied probability” is really a range, and round-tripping a position costs real money.

Depth matters the same way: a big order in a shallow book moves the price against itself. Volume and liquidity figures — both shown on Knoww market pages — tell you how much weight a price can bear.

Reading movement

A price is a snapshot; the change is the story. A market moving from 30¢ to 42¢ in a day is the crowd repricing new information — worth more attention than the level itself. But scale your reading to the market’s size: in a thin market, a few hundred dollars can produce the same 12-point move that would take serious capital in a deep one. Movement in a high-volume market is signal; movement in a tiny one may just be one trader.

Multi-outcome markets

Questions with several answers — who wins a nomination, which team takes a title — are structured as a set of binary markets, one per candidate. Each has its own Yes price, and the leader’s price is the headline probability. Two quirks to expect:

• The prices rarely sum to exactly 100%. Each outcome trades in its own book with its own spread, so the sum drifts a little above or below. Small deviations are structural, not a signal.
• Longshots are usually a touch expensive. The favorite–longshot bias means 2–5¢ candidates tend to be overpriced relative to their true chances. Treat sub-5% prices as “unlikely,” not as precise estimates.

The time factor

A share is a claim on $1 at resolution, so far-off markets price in the wait. A near-certain outcome resolving next week can trade at 99¢, while an equally certain one resolving next year sits at 95¢ — the 5¢ gap is largely the cost of locking up capital, not extra doubt. When comparing odds across markets, check the resolution date before reading small price differences as disagreement about probability.

A 30-second reading checklist

• Convert the price to a probability (cents → percent).
• Check volume and liquidity — how much weight can this price bear?
• Check the spread — is the probability a point estimate or a range?
• Check the 24-hour move — has news just repriced this?
• Check the resolution date — how much of the price is time?
• Read the resolution rules — the market settles on its written terms, not the headline. See how prediction markets resolve.

Then practice on live examples: the markets feed and category pages like politics and finance show all of these numbers on real, open markets. New to the subject entirely? Start with what is a prediction market.