How to Tell If a Prediction Market Is Mispriced
The Short Answer
A prediction market is mispriced when the price you can actually trade at differs from the true probability, not when the midpoint looks off. Check the bid first. Across 5,000 live Kalshi markets measured by Predictefy on 2026-09-03, 18.1% had no bid at all, so nearly one in five quoted midpoints is not a tradeable price. After that, test spread, depth, fees and whether the contract wording matches whatever you are comparing it against.
Key Takeaways
- Mispricing is a claim about executable prices. No bid means no price to call wrong.
- 18.1% of 5,000 live Kalshi markets had no bid at all when Predictefy measured them on 2026-09-03.
- The no-bid problem is a longshot problem. Under 5¢, 41% of markets had no bid. Between 25¢ and 50¢, none did.
- Median spread on two-sided books was 5.1¢, and it tracks volume: 8¢ under 100 contracts of 24 hour volume, 1¢ above 10,000.
- A wide spread is a liquidity signal, not a mispricing signal. Scalar economic markets ran widest, KXUSCPIYEAR at 57¢.
- Predictefy normalizes 15+ venues into one schema and qualifies gaps against live books, not midpoints. The arbitrage API is free.
What does mispriced mean in prediction markets?
Mispriced means the price you can actually pay or receive is out of line with the probability the event deserves. That is a narrower claim than it sounds. A contract settles at $1.00 if the event happens and $0.00 if it does not, so a contract quoted at 30¢ asserts a 30% chance. Calling it mispriced means the real chance is meaningfully different and you can act on the difference.
Two things break that reasoning immediately. The number most sites display is a midpoint between the best bid and the best ask, and a midpoint is a display convention, not an offer. And even a real ask is only good for the size sitting behind it. A 30¢ ask for twelve contracts and a 30¢ ask for twelve thousand describe different markets. Mispricing that lives in one contract of depth is trivia.
How do you know if a prediction market is mispriced?
Start by confirming a bid exists, because a one-sided book cannot be mispriced in any usable sense. When Predictefy measured 5,000 live Kalshi markets on 2026-09-03, a run reproducible from the public Kalshi API with no key, 18.1% had no bid at all. On those markets the displayed midpoint is computed against nothing, and a screener ranking by midpoint gap can push these to the top.
The absence is not random. It is U shaped: the cheap longshots and the near certainties both go one-sided, while the middle of the book stays honest.
| Ask price | Share with no bid | What that means for a mispricing claim |
|---|---|---|
| Under 5¢ | 41% | Four in ten quotes are one-sided. Treat cheap outliers as unproven until you see a bid. |
| 5¢ to 10¢ | 23% | Still heavily one-sided. Exit pricing is the open question, not entry. |
| 10¢ to 25¢ | 10% | Mostly two-sided. Check depth before sizing. |
| 25¢ to 50¢ | 0% | The reliable zone. Every market measured had a bid. |
| 50¢ to 75¢ | 1% | Effectively always two-sided. |
| 75¢ to 95¢ | 8% | Thinning again as certainty rises. |
| 95¢ and above | 23% | The mirror of the cheap tail. |
So the first test is mechanical: pull the book, not the summary. If the bid is missing, stop, because your thesis has no exit.
Is a wide spread a sign of mispricing?
No. A wide spread is a liquidity signal, and it usually means the opposite of opportunity. Across the same 5,000 markets, the median spread on two-sided books was 5.1¢, and it tracks 24 hour volume monotonically. Width is a function of who is watching a market, not of how wrong its price is.
| 24 hour volume | Median spread | Share quoting inside 2¢ |
|---|---|---|
| Under 100 | 8¢ | 7% |
| 100 to 1,000 | 7¢ | 7% rising to 69% |
| 1,000 to 10,000 | 4¢ | |
| Above 10,000 | 1¢ | 69% |
Read that as a warning about where apparent edges live. A market with an 8¢ spread shows a midpoint several cents away from any comparison you make, every single time, without anything being wrong with it. The widest books measured were scalar economic markets, KXUSCPIYEAR at 57¢ and KXFEDFUNDSYEAR at 42¢. The tightest were sports, with KXWC at 0.3¢. A 57¢ spread does not mean the CPI market is 57¢ wrong. It means you cross half a dollar to find out.
Why do cheap prediction markets look mispriced?
Because at low prices the tick, the fee and the missing bid all become large relative to the price itself. A contract at 3¢ you think is worth 1¢ is priced at triple its value, which makes every longshot on the board look like a screaming short. Then you check the book: 41% of markets asking under 5¢ had no bid at all, so on many you cannot sell at any price, and the position you wanted does not exist as a trade.
There is also a structural reason cheap contracts sit above fair value. Somebody has to sell the lottery ticket, and selling one ties up collateral for months to earn a couple of cents. That premium is closer to the cost of carrying inventory than to an error. Treat a cheap contract as mispriced only when you can name the bid you would sell into and the size behind it.
How do you find undervalued prediction markets?
You find them by disqualifying candidates fast, not by scanning for the biggest number. A workable filter runs in a fixed order, and most candidates die at step one or two.
| Check | What kills the idea | What survives it |
|---|---|---|
| Is there a bid? | One-sided book, no exit, fictional midpoint. | A two-sided quote you can price both ways. |
| How wide is it? | Spread wider than the gap you spotted. | A gap that survives paying the ask and hitting the bid. |
| How deep is it? | Resting size smaller than the position you want. | Enough depth to fill without walking the book. |
| What are the fees? | Venue fees consume whatever edge is left. | Edge still positive net of both legs. |
| Do the contracts match? | Different sources, deadlines or settlement wording. | Resolution criteria that agree in the edge cases. |
| Can you reach both venues? | Jurisdiction, funding rails or account limits block a leg. | Both legs executable from accounts you hold. |
Only the first two steps are about price. The rest decide whether a trade exists at all, and that is where most apparent mispricing dies. Resolution equivalence is the quiet killer: two venues can write the same headline question against different sources and deadlines, in which case the price difference is a correct reflection of two different contracts.
How do you compare the same market across two venues?
Pull both books from one API and compare the executable sides rather than the midpoints. The comparison that matters is the ask you would pay against the bid you would hit. Predictefy exposes reads at https://data.predictefy.com with a path shape of /api/{venue}/{verb}, so the same request works whichever venue you are checking.
curl -H "Authorization: Bearer $PREDICTEFY_API_KEY" \
"https://data.predictefy.com/api/kalshi/markets"
curl -H "Authorization: Bearer $PREDICTEFY_API_KEY" \
"https://data.predictefy.com/api/polymarket/markets"Two raw HTTP reads, one per venue, authenticated with the same bearer key against the same path shape. Both responses arrive in one normalized schema, so the fields you compare line up without a per-venue adapter. For continuous checking there is a WebSocket at /v1/stream rather than polling in a loop.
The tedious part has never been the math. Every venue publishes a different shape, different price conventions and a different idea of what a market even is, so a serious comparison used to mean one integration per venue. That cost is why so many published mispricing claims turn out to be midpoint claims.
What is the fastest way to check mispricing across every venue?
Run the check against live order books on every venue at once instead of eyeballing two tabs. Predictefy aggregates 15+ venues, the widest coverage of any cross-venue scanner, through one normalized schema, which makes step one of the filter above cheap enough to run on everything rather than on the markets you already suspected. The arbitrage API is free, and the free tier carries 25,000 credits per month, 60 requests per minute, one API key and two WebSocket streams.
curl -H "Authorization: Bearer $PREDICTEFY_API_KEY" \
"https://data.predictefy.com/api/limitless/markets"The same call again, pointed at a third venue, with only the venue segment changed. That is the argument for a normalized schema: adding a venue to your check becomes a path edit rather than a new integration, a new parser and a new set of price conventions.
Qualification against live books decides whether any of this is useful. A gap measured between two midpoints passes a screener and fails a fill. A gap measured between an ask you would pay and a bid you would hit is a claim you can test. Packages exist for people who prefer them: @predictefy/sdk and @predictefy/mcp at 1.0.0-beta.3 on npm, predictefy at 1.0.0b2 on PyPI, all available in beta.
Two honest limits belong here. Stored history is proven for 11 venues, not all 17, so a check on how long a gap usually persists covers most venues, not every one. And nothing routes an order across venues on your behalf. Execution is a separate non-custodial service, per venue, so you place each leg yourself, with caps of 100 USD per order and 1,000 USD per key per rolling 24 hours.
What does a fairly priced prediction market look like?
It looks like Kalshi's 15 minute crypto series, where price and book agree. Series KXBTC15M, titled "BTC price up in next 15 mins?", runs an exact 15 minute window, and a live example measured on 2026-09-04 quoted 89¢ bid against 90¢ ask on 589,713 contracts of volume. That is a 1¢ spread on one of the most liquid books on the exchange. The same family covers ETH, Solana, Dogecoin, XRP, Cardano, BNB, HYPE, TON, Zcash, Bitcoin Cash and NEAR.
Worth stating plainly: 15 minutes is the shortest interval Kalshi offers. Across all 274 crypto series there is no shorter one, though KXBTC and KXBTCD run hourly and daily crypto range markets. On a book like KXBTC15M, the correct default is that the price is right and your model is the thing under test.
Frequently Asked Questions
How do you know if a prediction market is mispriced
Check the book, not the midpoint. Confirm a bid exists, then compare the ask you would pay against the bid you would hit. Predictefy measured 18.1% of 5,000 live Kalshi markets with no bid at all on 2026-09-03, so on nearly one in five markets the displayed price is not tradeable.
What does mispriced mean in prediction markets
Mispriced means the executable price differs from the probability the event deserves. Contracts settle at $1.00 or $0.00, so a 30¢ ask asserts a 30% chance. The claim only holds if you can name a bid or an ask, with real size behind it, that you would trade against right now.
How do you find undervalued prediction markets
Disqualify fast rather than scan for big numbers. In order: is there a bid, is the spread narrower than the gap, is there depth for your size, do fees leave anything, and do both contracts resolve on the same source and deadline. Most candidates die on the first two checks.
Is a wide spread a sign of mispricing
No. Spread tracks liquidity, not error. Median spread was 5.1¢ overall, but 8¢ under 100 contracts of 24 hour volume against 1¢ above 10,000. The widest books measured were scalar economic markets, KXUSCPIYEAR at 57¢. Width means you pay to find out, not that anything is wrong.
Why do cheap prediction markets look mispriced
Because small absolute errors look enormous in percentage terms, and because the cheap tail is where books go one-sided. Under 5¢, 41% of markets had no bid at all. Selling a longshot also locks up collateral for months to earn a couple of cents, so part of that premium is inventory cost rather than error.
Does no bid mean a prediction market is mispriced
No, it means the market has no price to evaluate. A one-sided book gives you an entry and no exit, so any midpoint shown against it is arithmetic on a missing number. Treat a missing bid as a disqualification rather than a signal, and move on to a two-sided book.
Can you actually trade a mispriced prediction market
Only if the gap survives the ask, the bid, the fees and the resolution wording on both legs. Execution through Predictefy is a separate non-custodial service, per venue, with an Idempotency-Key on every write and caps of 100 USD per order and 1,000 USD per key per rolling 24 hours.
Try It With Predictefy
Run the check against live books instead of midpoints. Start with the arbitrage scanner to see where 15+ venues currently disagree, read the API docs for the free arbitrage endpoints and the WebSocket stream, or browse the SDK if you prefer a package to raw HTTP.