How to find neg-risk arbitrage on Polymarket
In mutually-exclusive market groups the leg prices should sum to about 100%. When they don't, a complete set is mispriced — buy every leg under $1 or sell every leg over $1.
Steps
- Switch the dashboard to the "Related & spreads" view.
- Sort by edge: groups where buying all legs costs under $1.00 (or selling brings over $1.00) float to the top, fee cushion already applied.
- Only groups where every leg has a live quote are flagged — partial groups are marked honestly as incomplete.
- Click "check depth" on a candidate: PrismTick pulls the order book for each leg and shows how many complete sets are executable at those prices.
- Execute on Polymarket leg-by-leg via the market links, starting with the thinnest book.
Why this works
The screener recomputes executable complete-set pricing from live best bids and asks across every loaded group — an angle the official interface doesn't surface at all.
FAQ
Why did the edge disappear when I checked depth?
Top-of-book prices can be for tiny size. Depth check reveals the real executable quantity; small displayed edges often cover only a few sets.
Is this risk-free?
No: execution risk (prices move between legs), fee assumptions and resolution edge cases all apply. Treat flagged groups as candidates to verify, not guaranteed profit.