How to Read a Cross-Market Gap Table
A gap table sorted by size is a list of artefacts. Here is the order to read one in, what each column means, and which rows to ignore first.
A table of cross-venue price differences is the most misreadable object on any prediction market site, including this one. The instinct is to sort by the biggest number. That instinct is precisely wrong.
The columns and what they mean
The two prices. Mid on each venue, computed from live quotes rather than last trades, ideally size-weighted where the books are lopsided.
The gap. The difference. This is a measurement, not a return.
The tradeable gap. What remains after crossing the spread on each side. Always smaller, sometimes zero, occasionally negative.
The equivalence grade. How comparable the two questions are. The most important column on the table. Equivalence grades.
Liquidity on each side. Size at top of book, or a depth measure. Determines whether the row means anything at scale. Depth and slippage.
Data age. How old each observation is. Determines whether the row means anything at all. Stale quotes and timing.
Time to settlement. Determines the capital cost, and therefore what the gap is worth annualised. Capital lockup.
The order to read in
One: grade. Discard everything below a good grade before looking at any price. A large gap on a poorly matched pair is not a finding; it is two different questions.
Two: data age. Discard anything stale on either side. This removes most of what survived step one.
Three: liquidity. Discard anything where the book is too thin to transact. This removes most of what survived step two.
Four: the tradeable gap, annualised over time to settlement. Now, finally, sort.
What is left is usually a handful of rows with small numbers. That is the honest output. A table that still has enormous numbers at the top after those four filters has a bug in it.
What the big numbers actually are
In descending order of frequency:
- one side has not traded recently and its quote is from a different world;
- the two questions differ in source, threshold, deadline or tie handling;
- one side has a one-sided or near-empty book and the mid is an invention;
- a multi-outcome set has been compared to a binary without summing the right subset;
- genuine disagreement between two populations of participants, which is real and is not an error. Why venues disagree.
Actual exploitable mispricing is at the bottom of that list, and it is small when it appears.
Why this site's table is short
Because the filters run before the table is rendered rather than being left to you. Pairs that cannot be structurally matched are not shown. Pairs with stale data on either side are marked. The default ordering is not by raw gap size.
The result looks less impressive than a naive comparison and is considerably more useful. Cross-market gaps is the table; the methodology is the reasoning behind it.
The phrase on every row
Theoretical cross-market edge. Each word is carrying weight. Theoretical: before costs and before anything goes wrong. Cross-market: it exists between two venues, not within one. Edge: a difference, not a return.
It is never profit and this site will never call it that, because the gap between the headline and the outcome is made of the four filters above plus every cost in what a gap is worth.
Next
Gap size versus liquidity — the relationship that explains the whole table.
Educational content only. Nothing here is financial advice, a solicitation, or an offer to trade. Prediction markets can move against you and a position can lose its entire value. Where this guide describes a difference between venues it describes a theoretical cross-market edge in observed prices, which is not a profit: fees, spreads, capital lockup, transfer time and differing settlement rules all come out of it first.
Keep reading
Cross-Market Gaps · 3 min readMatching Markets Across Venues Without GuessingBefore you can compare two prices you must establish that the two contracts are about the same thing. Structural matching, and why title similarity fails.
Cross-Market Gaps · 3 min readWhy the Biggest Gaps Are Always the Least LiquidPlot price difference against traded size and the shape is always the same. Understanding why explains most of what a cross-market table is showing you.
Cross-Market Gaps · 3 min readStale Quotes and Why Timing Ruins ComparisonsThe largest source of phantom cross-market opportunity is not disagreement. It is one price being older than the other. How to measure and exclude it.
What Markets Price · 3 min readCrypto Price Markets and Why They Are Harder Than They LookThe underlying trades continuously on a dozen venues. That makes the settlement source, the timestamp and the reference price the whole ballgame.