Order book, ticker and trades

Three topics carry market data, the same for every participant, in the same wire format as the account channels and the REST API.

Topic	Carries	Filters
orderbook	aggregated book levels	market_ids (required)
ticker	per-market price summary	sports, competitions
trades	executed trades, anonymous	market_ids, event_ids

Each is a single topic covering every market, narrowed by the join payload. Watching ten markets is one join, not ten.

Field names

Money is a dollar string ("0.3900"), quantities are quantity strings ("100.00"), and counts are plain integers. Field names are snake_case throughout, and the offer side is called offer, not ask, the same names the REST market payload uses.

Filters

Every filter follows one contract:

• omitted, null, [], or a list with no usable entry means no filter;
• unusable entries are dropped rather than rejecting the join;
• the join reply echoes what was actually applied, so compare it against what you sent to catch a typo;
• naming two filters narrows: a message must match both;
• select_filters (or select_market_ids on orderbook) changes them without rejoining.

orderbook is the one exception: it requires at least one valid market_id.

orderbook

["1","1","orderbook","phx_join",{"market_ids":["<uuid>","<uuid>"]}]

An absent or unusable list is an error, not “no filter”:

{"status":"error","response":{"reason":"market_ids_required"}}

Pushes "book" on the matching engine’s publish cadence, one message per market:

{
  "market_id": "...",
  "bids": [{"price":"0.3900","quantity":"100.00","liquidity":"39.0000",
            "total_quantity":"100.00","total_liquidity":"39.0000"}],
  "offers": [],
  "timestamp": "2026-09-02T21:16:39.717812Z",
  "timestamp_us": 1788383799717812
}

Levels are best-first. liquidity is that level alone; total_quantity and total_liquidity are cumulative through it.

Every push is a full snapshot

This is not a delta protocol. Replace the book you hold for that market_id wholesale on each message rather than applying it incrementally.

Change markets without rejoining:

["1","2","orderbook","select_market_ids",{"market_ids":["<uuid>"]}]

The non-empty requirement still applies; an unusable list leaves the current selection in place and replies with an error.

ticker

["1","1","ticker","phx_join",{}]
["1","1","ticker","phx_join",{"sports":["Football"],"competitions":["NFL"]}]

Pushes "ticker" for each market whose price, book top, volume or open interest moved:

{
  "market_id": "...", "market_symbol": "STXNFL-...",
  "event_id": "...", "event_symbol": "STXNFL-...",
  "sport": "Football", "competition": "NFL",
  "last_traded_price": "0.3900", "last_traded_quantity": "100.00",
  "best_bid": "0.3800", "best_bid_quantity": "250.00",
  "best_offer": "0.4000", "best_offer_quantity": "175.00",
  "bid_depth": 4, "offer_depth": 6,
  "open_interest": "1200.00", "total_volume": "48000.00",
  "timestamp": "...", "timestamp_us": 1788383799717812
}

bid_depth and offer_depth count price levels, so they are integers rather than quantity strings. Any field can be null on a market that has not traded or has an empty side of the book. event_symbol is null while the event list is still warming.

Filter values are matched exactly as the market carries them, so "Football" and "football" are different.

No snapshot on join

This is a change feed; nothing arrives until a market moves. Fetch GET /api/v1/markets for the initial state, then keep it current from here.

trades

["1","1","trades","phx_join",{}]
["1","1","trades","phx_join",{"market_ids":["<uuid>"],"event_ids":["<uuid>"]}]

Pushes "trade", one per execution:

{
  "market_id": "...", "market_symbol": "STXNFL-...",
  "event_id": "...", "event_symbol": "STXNFL-...",
  "price": "0.3200", "quantity": "100.00", "action": "buy",
  "timestamp": "...", "timestamp_us": 1788383799717812
}

action is the taker’s side: "buy" when the incoming order bought from the book, "sell" when it sold into it.

This feed is anonymous: it carries no account, user or order identifier for any market participant.

trades is not fills:{user_id}

trades is every trader’s executions; fills:{user_id} is yours. They differ by one letter and are not interchangeable.