Understand what the market is saying.
The rules, the book and the arithmetic behind a position.
Observable data. Clear assumptions.
Yield3 describes public market data. It does not forecast outcomes, recommend positions or execute trades; it holds no funds, keys or accounts, and it never asks to connect a wallet. It is not affiliated with Polymarket — where this page describes the venue, it describes what the venue publishes and what we have measured against it, with the measurements dated.
How are Polymarket's trading fees calculated?
The published taker fee is not a flat percentage. It is rate × p × (1 − p) × shares, assessed fill by fill at each fill's own price — largest at 50¢, vanishing toward the edges. On a buy the fee is taken in shares: you pay exactly the cash you entered and the payout shrinks. On a sell it comes out of the cash you receive.
The rate is per market, and sometimes it is not published at all. An unknown fee is never rendered as zero — every figure that would have included it is shown pre-fee and labelled "excludes fees". Zero is a claim; unknown is the absence of one.
Why is the price I pay higher than the price on the page?
Because the number on the page is a midpoint, and a midpoint is not a price anyone is offering. Buying walks the resting book from the best price outward, so your average fill is worse than the top of the book by an amount that grows with your size — that gap is the cost of the size, separate from the fee.
The visible book is finite: when an order is larger than what is resting, the remainder does not fill at a worse price — it does not fill at all until someone posts. And NO is priced by complement: buying NO at 18¢ is the same transaction as selling YES at 82¢, one ladder read from either end.
What is an effective breakeven?
Your all-in cost per share, read as a probability: the cash you put in, divided by the shares you actually end up holding. A 71.07¢ breakeven reads as: this trade needs the true probability to be above 71.07% to be worth taking; on a sell the direction flips.
When the fee is unknown it falls back to the pre-fee average and says so. It is arithmetic, not a view — it states what has to be true for a trade not to lose, and says nothing about whether that is likely.
How do I go short, and what is my stake?
There is no separate short instrument: you go short by buying the NO side, which costs 1 − p. That changes the yardstick — if YES trades at 82¢, NO costs 18¢, and 18¢ is the capital at risk. The same three-cent move is +16.7% on the NO stake and +3.7% on the YES side.
Every return figure on this site is stated against the capital actually committed, never in raw cents. The fee, note, is symmetric across the two sides — it is not what makes one side better.
Why don't the outcomes of one event add up to 100%?
Only a negative risk group — exactly one outcome can win — should sum to about 1.00. An event that is merely a list of related questions owes you nothing. Even inside a genuine group the on-screen sum is usually wrong: empty books quote artifact midpoints, placeholder legs pad the field, long listings get truncated, and a midpoint is not a price anyone can transact at across a dozen legs simultaneously.
A group price sum is published here only when the event is mutually exclusive, every leg carries a price, and the listing is not truncated. If any of that fails, no sum is published and the reason is stated in its place.
What actually decides the payout?
The settlement text does — not the title. Every market carries a paragraph stating the conditions under which it pays out; the title is a headline for that paragraph, and the two routinely disagree. The payout follows the text.
Nothing on this site paraphrases it. Where a summary is shown, it is a verbatim sentence lifted out of the text. A market that carries no settlement text gets no page here rather than a page with nothing in it.
Which sentence states the YES condition?
The settlement text is templated closely enough that one sentence usually carries the whole condition — "This market will resolve to 'Yes' if …". Where that sentence can be identified, it is quoted verbatim above the full text.
Measured over 800 real markets, about 26% produce one. The misses are mostly texts that state no per-leg condition — a shared group description, or an outcome pair that is not Yes/No at all — and for those the full text is shown with a note, instead of a widened pattern asserting a condition the text does not contain.
When does a market actually settle?
Two dates are published per market, and they are not interchangeable. The settlement deadline is the one settlement actually runs on, and is shown whenever it exists. The listed end date is administrative metadata and frequently inaccurate — it is never used here for anything time-sensitive: no countdown, no time-decay arithmetic.
Neither date guarantees the real-world answer is known by then. Markets still contested at the deadline are exactly where the settlement text — its named source and tie-break — does the work.
Where does the settlement answer come from?
Some markets name the specific publication, feed or official release the outcome will be read from; where one is named, it is shown verbatim. Many name nothing — the field is then shown as absent rather than filled with a plausible guess, because an inferred source would look exactly like a stated one.
That absence is itself information: read the full text and decide whether it is specific enough to be adjudicated the way you expect.
What if the settlement text changes after I have read it?
It can change, and a change to that paragraph is a change to the terms of the trade. This site stores a whitespace-normalised digest of each market's settlement text, so a real change is detectable without false alarms from reflowed prose. We hold no per-field history, so no "last changed" timestamp is shown — inventing one from record timestamps a volume tick can move would be a fabrication.
Whether you are told "this changed since you last looked" needs a remembered baseline. That comparison ships in the PolySmarter browser extension, which keeps your baseline locally; the web pages do not yet keep one.
Which price does this site show for a market?
The best evidence available, in a fixed order: a tight two-sided midpoint; else the last traded price — stale but real; else a wide midpoint — weak, but still a quote; else nothing at all, because a book spanning 90 or more percentage points carries no information and its midpoint is an artifact, not a weak signal.
Absence is shown as absence. A market with no published bid and a market bid at zero are different facts, and they are never merged into one.
What does "not covered" mean? It looks like an error
It is not an error. It is a normal cold state, and it is kept strictly apart from four others:
| State | What it means |
|---|---|
| Not covered | We hold no capture of that kind for this market. Nothing was computed, and nothing failed. |
| Insufficient sample | Something was computed and the sample is too thin to show. |
| Analysing | A pass is queued or running for this market. |
| Requires a paid plan | The data exists and this plan does not include it. |
| Error | An upstream failure. Not a synonym for "no data". |
Merging any two of these would leave the reader unable to tell whether to wait, to upgrade, to look elsewhere, or to report a bug.
$100 at 70¢.
What do you actually receive?
Using an illustrative published rate of 0.05, exponent 1, and a single fill.
Try the calculator- Cash spent
- $100.00
- Gross shares
- 142.86
- Fee value
- $1.50
- Shares deducted
- 2.14
- Shares received
- 140.71
- Effective breakeven
- 71.07¢
Glossary
- Mutually exclusive group (negative risk)
- A set of markets in one event where exactly one outcome can win. Their YES prices should sum to about 1.00, which makes the sum meaningful; in an event that is merely a list of related questions, it is not. See why the legs rarely add up on screen.
- Settlement deadline
- The date settlement actually runs on, as distinct from the administrative end date published beside it, which is frequently inaccurate. See when a market actually settles.
- Primary source
- The publication, feed, or official release a market names as where its outcome will be read from. Often absent, and shown as absent. See where the settlement answer comes from.
- Effective breakeven
- Cash in, divided by the shares actually held — your all-in cost per share, read as a probability. It answers "what would have to be true for this not to lose", and nothing else. See the full explanation.
- Book Lean
- Which side the resting order book structurally leans to, taking the size at each price level into account rather than only the best bid and best ask. It describes the current state of the book; it is not a probability forecast, and it is not a signal to act on. We call it Book Lean rather than microprice because nobody should have to learn an academic term before reading a chart.
- Executable Relative Value
- Whether a price deviation inside one event could actually be traded at a real size. A deviation measured on midpoints assumes every leg fills at its midpoint; walking each leg's book at a real size turns that into a larger execution cost and, usually, a much smaller deviation. It is the difference between a gap you can see and a gap you could act on. See reason 4 above.
- Not covered
- We hold no capture of that kind for this market — nothing was computed, and nothing failed. Distinct from an insufficient sample and from an error. See the five states.