01 · Venue mechanics
One position. Several conditions.
A leg is one outcome you add to the Combo. If you choose three legs, the Combo is contingent on all three—not a basket where two out of three is enough.
| Term | What it means | What it does not mean |
|---|---|---|
| Leg | A selected outcome inside the Combo. | A separate position that can be evaluated in isolation after you bundle it. |
| Combo | One multi-leg position whose outcome depends on every leg resolving your way. | A promise that individual market prices can simply be multiplied into an executable price. |
| Potential payout | What the Combo pays if every leg comes in. | The amount you keep — the taker fee comes off the top. |
02 · Bookie calculation
The multiplication is a benchmark, not a quote.
If you assume legs are independent, you multiply their probabilities. A 60% leg and a 70% leg produce an independence benchmark of 42%: 0.60 × 0.70 = 0.42. The chance that at least one fails is then 58%.
- Combined chance, under independence: multiply every leg probability.
- At least one leg fails: subtract that combined chance from 100%.
- A venue quote: a separate, current number, priced by a market maker through the venue’s own flow.
The Combo Lab keeps that distinction visible: entered leg probabilities are inputs to an explanatory calculation until a legitimate venue quote is available.
03 · Execution mechanics
A public catalog is not an executable quote.
Polymarket documents a public catalog of active Combo-leg markets. That can help a tool discover what to display, but it does not grant authority to submit a Combo, receive a quote, or execute a trade for someone.
The technical documentation describes an RFQ—request for quote—auction for Combos. An RFQ is a request for a counterparty price, not a completed trade. The same documentation marks requester support as coming soon and documents authenticated maker-side connectivity.
04 · Before resolution
“Cash out” means finding a buyer.
Polymarket says a Combo can be sold before resolution. That is different from a guaranteed exit: a current buyer or market-maker quote is needed for your specific position, size, and price. The displayed value can change while you review it.
- Read the current sell/cash-out state as a request to find a counterparty, not a guaranteed button.
- Check the exact Combo, size, and price shown by the venue before you confirm anything.
- If there is no quote, do not infer a hidden fair price from individual legs or from an old screenshot.
- Use the venue’s support path for account- or interface-specific problems; Bookie cannot inspect its private order flow.
See the focused guides on selling a Combo, why a sale may not be available, and a greyed-out button.
05 · Common questions
The questions worth asking before the click.
Are individual market prices the same thing as a Combo price?
Is there a verified maximum number of Combo legs?
Does a grey button mean the Combo is bad?
Can I use this guide to bypass availability restrictions?
06 · Update history
A maintained reference needs a visible paper trail.
| Reviewed | What changed | Source basis |
|---|---|---|
| August 11, 2026 | Initial guide: mechanics, current documented sports scope, RFQ boundary, early-sale guidance, and probability caveats. | Polymarket Help Center and developer documentation linked below. |
We update this history when a source changes the substance of the guide. A deploy alone is not an update; a current primary source is.