How markets work

Every market on the STX exchange is a binary outcome contract: it either resolves yes or no. When a market resolves, every outstanding contract settles at either the market’s max_price or at $0. The market’s description field is the definitive statement of what constitutes a “yes” result:

{
  "description": "Contracts for this market settle into $1 if the Boston Red Sox beats the New York Yankees by at least 1.5 runs and $0 if they do not.",
  "market_id": "becf9bf9-e2ff-4b50-879b-46054ad5c69a",
  "short_title": "NYY @ BOS -1.5"
}

Buying a contract means you believe the outcome described will happen. Selling means you believe it won’t. You are always trading against other participants on the exchange, not against STX.

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Prices

Prices are dollar amounts sent as strings. A price of "0.45" means $0.45, and an order price takes at most two decimal places. The spread between the best available bid and offer represents the current market consensus.

The REST API writes every money field this way, and quantities as decimal strings:

{
  "max_price": "1.0000",
  "bids":   [{"quantity": "566.00", "price": "0.5300"}],
  "offers": [{"quantity": "3636.00", "price": "0.6700"}]
}

The order book channel, market:<market_id>, sends those levels in dollars too but in its own abbreviated shape. order_book_update carries ob.b and ob.o, and each level is {p, q, l, tc, tl} (price, contracts, liquidity, and the cumulative contracts and liquidity through that level), with every value a JSON number, not a string:

{"ob": {"b": [{"p": 0.53, "q": 566,  "l": 299.98,  "tc": 566,  "tl": 299.98}],
        "o": [{"p": 0.67, "q": 3636, "l": 2436.12, "tc": 3636, "tl": 2436.12}]}}

The markets and market_updates channels are different again: their bids[].price and offers[].price are in cents (53), not dollars. All three formats side by side are in Mapping markets.

Over REST a book price can go straight into an order: "0.5300" from bids is a valid price. Only the markets and market_updates channels need converting from cents.

The max_price field on a market is the settlement value for a winning contract, in dollars. It is also the reference point for calculating sell-order liability (see Understanding Positions).

Read max_price from each market rather than assuming it. New markets settle at $1, so max_price is "1.0000" and a contract trades between $0.01 and $0.99, but older markets carry other values and one environment can hold both. An order priced at or above a market’s max_price is rejected.

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Market Status

Status	Meaning
scheduled	Created; no orders accepted yet
pre_open	Accepts limit orders ahead of open; no trades yet
open	Orders can be placed and matched
closed	The result is known; no new orders, and resting orders are cancelled
resulted	Result confirmed; settlements generated
cancelled	Cancelled; no new orders, and resting orders are cancelled
voided	Cancellation confirmed; void settlements generated

A response can also read suspended, which is not a stored status: an open or pre_open market that is not trading right now. archived is a separate boolean field, not a status. See Market and order status for the full detail.

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Querying Markets

Use the GET /api/v1/markets query to fetch current markets. It is signed like every other /api/v1 route, and heavily cached, so you can call it frequently; it is designed to handle high query rates.

For a price display or market screener, see List markets for the request, response and a runnable curl.

The best bid and offer are enough to estimate the implied probability of the outcome. For example, on a market whose max_price is "1.0000", a best bid of "0.5700" and a best offer of "0.6000" mean the market is trading at 57 to 60 cents, roughly a 57 to 60% probability of the “yes” outcome.

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Real-Time Updates

Querying GET /api/v1/markets gives you a snapshot. To receive live price and status changes without polling, subscribe to the markets WebSocket channel, which pushes only the changed fields whenever a market is updated.