Binary YES/NO markets
Every market asks one question with exactly two outcomes: YES or NO. Each market has two contracts:- A YES contract pays 1.00 USDC if the outcome is YES, and 0 if NO.
- A NO contract pays 1.00 USDC if the outcome is NO, and 0 if YES.
Prices are probabilities
A contract’s price is always between 0.01 and 0.99, and it reads directly as the market’s estimated probability of that outcome.
Because YES and NO are the two halves of the same question, their prices always
sum to 1.00:
0.65, NO is 0.35. Buying NO at 0.35 takes the opposite
view to YES at 0.65 — the two prices are two readings of one question.
The combined order book
Calibri does not keep a separate book for NO. There is one combined order book per market, priced in YES terms, and the YES+NO=1.00 identity is enforced by construction. This keeps liquidity in one place instead of splitting it across two half-empty books. Because a YES and a NO contract together always pay 1.00, buying YES at0.60
is the same trade as selling NO at 0.40. So a resting YES bid at 0.60 is
also NO on offer at 0.40. A YES buyer can be filled by someone selling YES or
by someone buying NO; in the second case a new YES/NO pair is created for the
two of them. See The combined order book
for all four order kinds and what each match does.
What a contract is
A contract is created the moment the engine matches a YES buyer with a NO buyer. Their two payments, which add up to 1.00 USDC, go into the market’s escrow: one member holds the YES side, the other holds the NO side, and together their stakes fund the full 1.00 USDC that the winner will eventually collect. Once created, a contract can change hands — a holder can sell it to another buyer — and settlement pays whoever holds the winning side.- Your position in a market is the set of contract legs you hold (net YES, net NO, or flat).
- You can hold a position to resolution or sell it before then. Buying the opposite side does not net against the first — each leg is collateralised independently, so it locks additional capital instead of returning any.
Settlement — winner takes 1.00, loser takes 0
When a market resolves, each contract pays out:Market lifecycle
From a trader’s point of view, a market moves through these stages:1
Open
The market is live. You can place, fill, and cancel orders; prices move as
people trade.
2
Closed
Trading stops at the market’s close time. Open orders stop matching and your
positions are locked in, pending the outcome.Closing is not the same as answering. Where the outcome only becomes knowable
some time after close, the market states an answer deadline up front — see
Market resolution.
3
Resolved
The outcome is determined and contracts pay out — winners 1.00/share, losers
0. This is the normal end state.
4
Voided (exception)
If a market can’t be resolved fairly, it is voided: every share pays
0.50, YES and NO alike, and the taker fee is returned. That is not a refund
of what you paid — see Voids and postponements.
The four stages above are the summary; the API reports finer-grained statuses within them. Resolution runs on-chain through an escalation ladder — see Market resolution.
Putting it together
Related
Fees
The single taker fee, charged once at the trade.
Rewards
Maker rebates and referral rewards.
Recurring markets
Series, windows, and price-feed markets.
How markets are resolved
The data source behind each market type.
Placing orders
Placing a signed limit order in practice.
API Reference
Market, order-book, and ticker endpoints.