How a combo works
On an event-contract exchange, a single contract pays $1 if its outcome happens and $0 if it doesn't. Its price in cents is the market's estimate of the chance: a 62¢ contract is a 62% chance.
A combo joins two or more of those outcomes, called legs, into one contract. It pays $1 only if every leg settles yes. If any leg misses, the whole combo settles at $0. Sportsbooks call the same structure a parlay.
How a combo is priced
If the legs are unrelated, the chance that all of them happen is their chances multiplied. Three legs at 62¢, 58¢ and 70¢ multiply to 0.62 × 0.58 × 0.70 = 0.252, so a fair combo price is about 25.2¢.
You usually don't see a live order book for your combo. You request a quote, market makers respond, and you can accept it or pass. Quotes generally sit above the legs multiplied. The difference is what the bundle costs you.
| Leg | Price | As a probability |
|---|---|---|
| Team A wins | 62¢ | 0.62 |
| Team B wins | 58¢ | 0.58 |
| Team C wins | 70¢ | 0.70 |
| Legs multiplied | 25.2¢ | 0.252 |
| Example quote | 29.0¢ | 3.8¢ (15%) above |
Why traders use combos
- A bigger payout for a smaller cost. Three 60¢ legs cost $1.80 together; a combo on all three costs a fraction of that.
- One position instead of several. A combo settles once, when the last leg does.
What to watch for
- The markup compounds. A small markup on each leg grows with every leg you add. At 3% per leg, a 6-leg combo is about 19% over fair.
- Related legs change the fair price. Legs from the same game often move together, so the legs-multiplied number is only a starting point. See same-game combos.
- Fees weigh more on cheap contracts. Combos are usually low-priced, so the fee is a larger share of what you pay. See how fees change your break-even.
- You may not be able to sell. Some combos have no market to sell into before they settle. Hedging the last open leg is often the only way to manage one. See hedging the last leg.
