binary_option.md

Binary Option

BinaryOption represents a binary outcome instrument that settles to a fixed payoff based on whether a condition is true. It can model prediction markets, binary options, or venue-specific yes/no contracts.

Examples include prediction market outcomes and binary event contracts.

Fields

Field	Rust type	Python type	Required/default	Notes
instrument_id	InstrumentId	InstrumentId	Required	Stored as id in Rust.
raw_symbol	Symbol	Symbol	Required	Native venue symbol.
asset_class	AssetClass	AssetClass	Required	Asset class of the outcome market.
currency	Currency	Currency	Required	Quote and settlement currency.
activation_ns	UnixNanos	int	Required	Contract activation timestamp.
expiration_ns	UnixNanos	int	Required	Contract expiration timestamp.
price_precision	u8	int	Required	Decimal places allowed for prices.
size_precision	u8	int	Required	Decimal places allowed for order sizes.
price_increment	Price	Price	Required	Smallest valid price step.
size_increment	Quantity	Quantity	Required	Smallest valid size step.
outcome	Option<Ustr>	str | None	None	Outcome label when the venue provides it.
description	Option<Ustr>	str | None	None	Human‑readable market description.
max_quantity	Option<Quantity>	Quantity | None	None	Maximum order quantity.
min_quantity	Option<Quantity>	Quantity | None	None	Minimum order quantity.
max_notional	Option<Money>	N/A	Rust only	Maximum order notional value.
min_notional	Option<Money>	N/A	Rust only	Minimum order notional value.
max_price	Option<Price>	N/A	Rust only	Maximum valid quote or order price.
min_price	Option<Price>	N/A	Rust only	Minimum valid quote or order price.
margin_init	Option<Decimal>	N/A	Rust only	Initial margin rate.
margin_maint	Option<Decimal>	N/A	Rust only	Maintenance margin rate.
maker_fee	Option<Decimal>	Decimal | None	0	Maker fee rate. Negative values rebate.
taker_fee	Option<Decimal>	Decimal | None	0	Taker fee rate. Negative values rebate.
tick_scheme_name	N/A	str | None	None	Registered variable tick scheme name.
info	Option<Params>	dict | None	None	Adapter metadata.
ts_event	UnixNanos	int	Required	Event timestamp in nanoseconds.
ts_init	UnixNanos	int	Required	Initialization timestamp in nanoseconds.

Note: Python constructors use instrument_id; Rust stores the same value as id.

Behavior

• BinaryOption has instrument class BinaryOption.
• It is never inverse and uses a multiplier and lot size of one.
• Many venues quote binary outcomes between zero and one, but the venue defines the allowed price range and tick size.
• outcome and description provide human-readable context for the contract.

Example

<Tabs items={['Rust', 'Python']}>

use nautilus_model::instruments::BinaryOption;

fn outcome_label(instrument: &BinaryOption) -> String {
    instrument.outcome.map_or("unknown".to_string(), |value| value.to_string())
}

from nautilus_trader.model.instruments import BinaryOption


def outcome_label(instrument: BinaryOption) -> str:
    return instrument.outcome or "unknown"

Adapters

Representative adapters that create or consume BinaryOption instruments include:

• Hyperliquid for binary and prediction-style markets.
• OKX for venue-defined binary outcome products.
• Polymarket for prediction market outcomes.

Related guides

• Order Book covers binary market order book behavior.
• Data explains market data that references instruments.