What happens to your position if a market is delisted before it resolves?
Here is a situation with no obviously right answer, which is why it is worth writing about.
You hold a position in an outcome market. It has not resolved. The venue removes the market — the event was cancelled, or the listing was migrated, or the whole set was replaced. The last price it traded at was forty cents. What is your position worth?
Why the last price is the wrong answer
The tempting answer is forty cents. It is the last thing the market said, it is a number, and using it makes the problem disappear.
It is also wrong, and the reason is worth being precise about. A contract that pays either zero or one is never actually worth forty cents at settlement. Forty cents was the price at which the last buyer and the last seller disagreed about which of the two it would be. Settling every holder at that price pays out an amount that was never a possible outcome — everyone who was going to be wrong gets paid something, and everyone who was going to be right gets shortchanged.
Worse, it is a silent error. The position closes, a number lands in the balance, nothing fails, and no one has any particular reason to look at it again. Compared with a position that visibly refuses to settle, a confidently wrong settlement is the more expensive outcome by a wide margin.
So the design question is not "what number do we use?" It is "under what circumstances do we actually know the answer, and what do we do when we do not?"
Two kinds of evidence
BT365's settlement path for delisted HIP-4 markets looks for two independent sources, strongest first.
The strongest is mechanical. Many outcome markets are not opinions about events — they are price questions with a defined rule, such as whether an asset finished above a strike or inside a bucket at expiry. For those, the result is a function of the underlying price at expiry and the market's own bounds. Given the market's descriptor and a price reading from near expiry, the terminal value is known — and, critically, known regardless of the mark it happened to delist at. A bucket that was trading at fourteen cents can be settled correctly to one if the underlying finished inside it. The market being mid-priced when it vanished tells you what traders believed, not what happened.
The weaker one is a near-terminal price. If the market delisted at or above 0.9, or at or below 0.1, the market had effectively already decided, and that price can stand in for the outcome. This covers markets with no mechanical rule to appeal to — event and sports outcomes, where there is no underlying price to check against a strike.
The second test alone was the original implementation, and it works right up until a market delists in the middle, which is exactly when you need it most. Adding the mechanical path is what turned a class of stranded positions into correctly settled ones.
When the two disagree, believe neither
The rule that makes this trustworthy is the one governing conflict.
When both sources are available, they have to agree. If the mechanical result says one and the delisting price was 0.05, something is wrong — the descriptor was parsed incorrectly, or the price reading is off, or the mark is from the wrong market. Any of those is a bug, and none of them is resolved by picking the more convincing of the two.
So a conflict does not settle. It leaves the position open and raises it for review. This is a deliberate choice to prefer a visible unresolved position over an invisible wrong one, and it is the same choice as declining to settle at the mid price, applied one level up.
The same applies when neither source is available: a market that delisted mid-range with no mechanical rule to appeal to — a genuine void or cancellation, or an outcome pinned at the money — is left open and surfaced for manual repair. There is no fallback that guesses. That is the point.
Waiting is part of it
One more guard, less conceptually interesting but responsible for most of the correctness in practice.
A market that has stopped appearing in the venue's data has not necessarily been delisted. It might be a temporary gap, a partial response, or a read that raced a venue-side update. Treating the first absence as a delisting means settling live positions on the strength of a missing field.
So absence has to persist for a required window before it counts as a delisting, and that window is longer for markets whose expiry could not be established — if we cannot tell whether the market should have ended, we are more willing to keep waiting than to act. Only after the absence has held long enough does the evidence-gathering above run at all.
What this means if you hold one
Three practical points.
A position that stays open after a market disappears is not necessarily stuck. It may be inside the waiting window, which is doing real work. Settling faster would mean settling on weaker evidence.
A position that stays open for a long time may be genuinely undecidable, and that is what the manual repair path exists for. The alternative was never "settle it correctly, sooner" — it was "settle it wrongly, sooner".
Delisting risk is specific to venue-listed outcome markets. Where the outcome is an on-chain token, resolution is recorded on-chain and there is no listing to withdraw. That venue also has a redemption step that can fail and need retrying, so neither arrangement is strictly safer — but the failure you are exposed to is different, and worth knowing which one you have.
The general principle is the one worth taking away, and it is not specific to prediction markets: in a system that moves money, an unresolved state you can see beats a resolved state that is wrong. The first is an operational problem. The second is a loss nobody notices.
Part of our guide to how prediction markets actually work.
BT365 runs prediction markets on both Polymarket and Hyperliquid, alongside perps and spot, from one self-custodial account. Explore the platform or read the documentation.