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Core Concepts

Core Concepts

Prediction markets let you trade contracts whose value depends on the outcome of a defined event. A contract is a time-bound position on whether a proposition resolves YES or NO.

The mental model

Think of a prediction market as a question with tradable answers:

Code
Event (the question)
└── Contract / instrument (the proposition, expressed in YES space)
    ├── YES position
    └── NO position

• Event: The question being resolved, including rules, timing, and resolution source (e.g., "Will BTC settle at or above $100,000?").
• Contract: A tradable instrument representing one proposition within an event. Instruments are defined in YES space: the label, ticker, and symbol define what resolving YES means.
• Outcome: The contract side: yes or no. The outcome describes position exposure, not order direction (buy or sell).
• Position: Your quantity of a contract outcome. You can open, reduce, or close positions by trading the instrument.

The event defines the question. The contract defines the YES-space proposition. The outcome defines your YES or NO exposure.

To discover events and inspect contracts, use List Events and Get Event. For ticker formats, see Ticker Overview.

YES and NO positions

For a binary contract, YES and NO are complementary outcomes on the same tradable instrument:

Position	Resolves to a payout when the event...
YES	Resolves in favor of the stated proposition
NO	Does not resolve in favor of the stated proposition

For example, consider an event containing this contract:

Will the Federal Reserve lower its target rate by at least 0.25% at the specified meeting?

The API returns this instrument:

Code
GEMI-FEDJAN26-DN25

Buying yes expresses that the proposition will resolve YES. Buying no expresses that it will resolve NO. Both orders use the same YES-space instrumentSymbol; the outcome field selects your exposure.

If the contract resolves YES, the YES outcome pays the defined settlement amount. If it resolves NO, the NO outcome pays instead. Always check event resolution rules and metadata for settlement details.

instrumentSymbol

instrumentSymbol is the complete, exchange-recognized identifier for a tradable contract. It includes the GEMI- prefix, event identifier, and contract suffix:

Code
GEMI-FEDJAN26-DN25

Use the returned instrumentSymbol when requesting market data or placing orders. Do not infer symbols by concatenating event strings. Discover contracts through event endpoints to retrieve the exact symbol. See Ticker Overview for ticker structures.

Price as market-implied probability

Prediction-market prices are quoted in the contract’s settlement currency. For a binary contract with a $1.00 settlement value, a YES price of $0.65 indicates an implied probability of 65%:

Code
implied probability ≈ contract price / settlement value
                     ≈ $0.65 / $1.00
                     ≈ 65%

This calculation interprets current market price, not a guaranteed probability. Public order books are normalized in YES space. To calculate NO price, use 1 - yesPrice. Spreads, liquidity, and book depth determine executable prices.

For the complementary NO outcome, the implied probability is the remaining percentage. In practice, YES and NO prices may not total exactly $1.00 due to spreads and market depth.

Read event and contract definitions before comparing prices to external probability models.

Prediction contracts versus underlying assets

Prediction-market contracts can reference underlying assets (e.g., BTC, ETH, commodities, sports teams), but they do not grant asset ownership.

Prediction-market contract	Underlying asset ownership
Exposure is to a defined event outcome	Exposure is to asset market value or ownership rights
Settles to a fixed amount per contract rules	Value fluctuates continuously with the asset
Does not represent physical or tokenized units	Represents the asset itself or a direct claim
Identified and traded via instrumentSymbol	Traded on spot/derivative markets with asset custody

For example, buying the YES outcome on a BTC prediction contract does not purchase BTC. It creates exposure to the contract resolution condition. The contract can expire worthless even if BTC rises if the resolution condition is not met.

Before trading, use List Events to find events, Get Event to read definitions, and Ticker Overview to verify symbols.