> ## Documentation Index > Fetch the complete documentation index at: https://docs.cdp.coinbase.com/llms.txt > Use this file to discover all available pages before exploring further. # Coinbase Derivatives: Predictions FIX Market Data Messages The Coinbase Derivatives: Predictions FIX Market Data API lets you subscribe to order books, public trades, trade volume, open interest, and instrument status changes over FIX 5.0 SP2. ## Market Data Message Types The Coinbase Derivatives: Predictions Market Data FIX API supports the following message types. For Logon, heartbeats, and sequence recovery, see [Session](/derivatives-predictions/fix/session). > **Client Message Types** > > * [MarketDataRequest (35=V)](#marketdatarequest-35v): Subscribes to or unsubscribes from market data. > **System Message Types** > > * [MarketDataSnapshotFullRefresh (35=W)](#marketdatasnapshotfullrefresh-35w): Initial order book snapshot. > * [MarketDataIncrementalRefresh (35=X)](#marketdataincrementalrefresh-35x): Order book changes, trades, trade volume, and open interest. > * [MarketDataRequestReject (35=Y)](#marketdatarequestreject-35y): Rejection of a `MarketDataRequest`. > * [SecurityStatus (35=f)](#securitystatus-35f): Instrument trading status changes. > * [BusinessMessageReject (35=j)](#businessmessagereject-35j): Rejection of a malformed or unsupported application message. > **Session Message Types** > > Logon (35=A), Logout (35=5), Heartbeat (35=0), TestRequest (35=1), ResendRequest (35=2), Reject (35=3), and SequenceReset (35=4). See [Session](/derivatives-predictions/fix/session). ## Connection Connect with `TargetCompID (56) = CPMMD` and your API key in `SenderCompID (49)`. The API key must have the `MARKET_DATA` permission. You can open several sessions with one API key; see [Multiple sessions per API key](/derivatives-predictions/fix/session#multiple-sessions-per-api-key). Host and port are listed on the [Coinbase Derivatives: Predictions Connectivity](/derivatives-predictions/connectivity) page. Header fields are on [Header/Trailer](/derivatives-predictions/fix/header-trailer). Logon, the Logon signature, heartbeats, and sequence recovery are on [Session](/derivatives-predictions/fix/session). SendingTime (52) and TransactTime (60) on messages you receive are UTC timestamps with microsecond precision. ## MarketDataRequest (35=V) Subscribes to or unsubscribes from market data for one or more instruments, or for all instruments. | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 262 | MDReqID | String | Y | Unique client ID for the request. Echoed on every response for the subscription and used to unsubscribe. Must be unique among active subscriptions on the session. | | 263 | SubscriptionRequestType | Char | Y | `1` = Snapshot plus updates (subscribe). `2` = Disable previous snapshot plus updates (unsubscribe the `MDReqID`). Other values are rejected. | | 264 | MarketDepth | Int | C | Order book depth. `0` = Full book. `1` = Top of book (best bid and best offer). `10` = Top 10 levels per side. Required when MDEntryType (269) includes `0` or `1`. Not allowed otherwise. | | 267 | NoMDEntryTypes | NumInGroup | Y | Number of entry types requested. Must be at least `1`. | | → 269 | MDEntryType | Char | Y | Data to subscribe to. `0` = Bid (YES bids). `1` = Offer (NO bids). `2` = Trade. `B` = Trade volume. `C` = Open interest. `L` = Instrument lifecycle (specific to Coinbase Derivatives: Predictions). See [Entry types](#entry-types). | | 146 | NoRelatedSym | NumInGroup | Y | Number of instruments. `0` = All instruments (send no Symbol entries). A value greater than `0` must equal the number of distinct `Symbol (55)` entries. `0` is not allowed when MDEntryType (269) includes `0` or `1`. | | → 55 | Symbol | String | C | Instrument ticker or numeric instrument ID. Required when `146` is greater than `0`. | ### Entry types | MDEntryType (269) | Data | Scope | Response messages | | :- | :- | :- | :- | | `0` = Bid | Order book, YES bids | Per instrument only | One 35=W snapshot, then 35=X updates | | `1` = Offer | Order book, NO bids, priced as the NO price | Per instrument only | One 35=W snapshot, then 35=X updates | | `2` = Trade | Public trades | Per instrument or all instruments | 35=X only | | `B` = Trade volume | Total contracts traded | Per instrument or all instruments | 35=X only | | `C` = Open interest | Number of open contracts | Per instrument or all instruments | 35=X only | | `L` = Instrument lifecycle | Instrument trading status | Per instrument or all instruments | 35=f only | > [!NOTE] > > Request instrument lifecycle (`269=L`) on its own `MDReqID`. A request that combines `269=L` with any other entry type is rejected with `281=8`. > [!NOTE] > > Only order book requests (`269=0` or `1`) receive an initial 35=W snapshot. Trade, trade volume, open interest, and lifecycle subscriptions deliver only changes that occur after you subscribe. * A multi-instrument request is all-or-nothing: if any Symbol (55) does not resolve, or a snapshot cannot be delivered, the whole request is rejected and no subscription is created. * To unsubscribe, send `263=2` with the `MDReqID` of the subscription. All instruments subscribed under that `MDReqID` are removed. ## MarketDataSnapshotFullRefresh (35=W) Sent once per instrument when you subscribe to the order book (`269=0` or `1`). The snapshot contains only the requested sides, up to the requested MarketDepth (264). | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 262 | MDReqID | String | Y | `MDReqID` of the subscription. | | 55 | Symbol | String | Y | Instrument ticker. If the instrument has no ticker, the numeric instrument ID. | | 48 | SecurityID | String | Y | Numeric instrument ID. | | 268 | NoMDEntries | NumInGroup | Y | Number of price levels in the snapshot. `0` when the requested sides are empty. | | → 269 | MDEntryType | Char | Y | `0` = Bid (YES bid). `1` = Offer (NO bid). | | → 1023 | MDPriceLevel | Int | Y | Rank of the level within its side. `1` = Best price. | | → 270 | MDEntryPx | Price | Y | Price of the level, 3 decimal places. Offer (`269=1`) levels are expressed as the NO price, `1.000` minus the YES ask price. | | → 271 | MDEntrySize | Qty | Y | Quantity resting at the level, 2 decimal places. | | 60 | TransactTime | UTCTimestamp | Y | UTC time of the last event that changed the book, in microseconds. Sent once per message, not per entry. | ## MarketDataIncrementalRefresh (35=X) Carries order book level changes, trades, trade volume, and open interest. Each message carries one kind of update: order book levels, one trade, or trade volume and open interest. | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 262 | MDReqID | String | Y | `MDReqID` of the subscription. | | 268 | NoMDEntries | NumInGroup | Y | Number of entries in the message. | | → 279 | MDUpdateAction | Char | Y | `0` = New. `1` = Change. `2` = Delete. Trade, trade volume, and open interest entries are always `0`. | | → 269 | MDEntryType | Char | Y | `0` = Bid (YES bid). `1` = Offer (NO bid). `2` = Trade. `B` = Trade volume. `C` = Open interest. | | → 55 | Symbol | String | Y | Instrument ticker. If the instrument has no ticker, the numeric instrument ID. | | → 48 | SecurityID | String | Y | Numeric instrument ID. | | → 1023 | MDPriceLevel | Int | C | Rank of the level within its side. `1` = Best price. Sent on order book entries with `279=0` or `279=1`. Not sent on `279=2`. | | → 270 | MDEntryPx | Price | C | Price, 3 decimal places. Sent on order book and trade entries. Offer (`269=1`) levels are expressed as the NO price. Trade (`269=2`) prices are the YES price. Not sent on trade volume (`269=B`) or open interest (`269=C`). | | → 271 | MDEntrySize | Qty | Y | 2 decimal places. | | → 278 | MDEntryID | String | C | Trade ID. Sent on trade entries (`269=2`). Unique per execution; use it to deduplicate. | | → 2446 | AggressorSide | Int | C | Side of the aggressor on trade entries (`269=2`). `0` = No aggressor (opening fill). `1` = Buy. `2` = Sell. Not sent when the side is unknown. | | 60 | TransactTime | UTCTimestamp | Y | UTC time of the event, in microseconds. Sent once per message, not per entry. | > [!NOTE] > > Order book entries carry the absolute quantity at the price level. Replace your local level with `MDEntrySize (271)`; do not add or subtract. `279=2` removes the level. > [!NOTE] > > The gateway sends `279=2` only when a level's resting quantity drops to zero. When better prices push a level out of your requested depth, no Delete is sent; truncate your local book to the requested depth. > [!NOTE] > > Trade volume (`269=B`) and open interest (`269=C`) are sent with `279=0`. At settlement, the message may carry only open interest (`269=C`), without trade volume. ## MarketDataRequestReject (35=Y) Sent when a `MarketDataRequest` is well-formed but cannot be accepted. No subscription is created. | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 262 | MDReqID | String | Y | `MDReqID` of the rejected request. | | 281 | MDReqRejReason | Char | N | Reason for the rejection. See the values below. | | 58 | Text | String | N | Human-readable reason. Distinguishes conditions that share one `281` value. | | MDReqRejReason (281) | Sent when | | :- | :- | | `0` = Unknown symbol | A Symbol (55) does not resolve to an instrument, an unsubscribe (`263=2`) names an `MDReqID` with no active subscription, or the request could not be processed. | | `1` = Duplicate MDReqID | The `MDReqID` is already active on this session. | | `2` = Insufficient bandwidth | An order book snapshot could not be delivered. No subscription is created; retry the request. | | `4` = Unsupported SubscriptionRequestType | SubscriptionRequestType (263) is not `1` or `2`. | | `5` = Unsupported MarketDepth | MarketDepth (264) is missing or has an unsupported value on an order book request, or is present on a request without `269=0` or `269=1`. | | `8` = Unsupported MDEntryType | An MDEntryType (269) is unknown or not supported, NoMDEntryTypes (267) is `0`, or `269=L` is combined with other entry types. | | `9` = Unsupported scoping | NoRelatedSym (146) is missing or negative, the number of distinct Symbol (55) values does not equal `146`, or `146=0` is sent with `269=0` or `269=1`. | ## SecurityStatus (35=f) Sent to instrument lifecycle subscriptions (`269=L`) when an instrument is created or its trading status or symbol changes. No snapshot is sent on subscribe. | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 55 | Symbol | String | Y | Instrument ticker. If the instrument has no ticker, the numeric instrument ID. | | 48 | SecurityID | String | Y | Numeric instrument ID. | | 326 | SecurityTradingStatus | Int | Y | Instrument trading status. See [SecurityTradingStatus values](#securitytradingstatus-values). | | 60 | TransactTime | UTCTimestamp | Y | UTC time of the status change, in microseconds. | ### SecurityTradingStatus values Coinbase Derivatives: Predictions assigns its own meanings to SecurityTradingStatus (326). Interpret the values by this table, not by the standard FIX descriptions. | Value | Status | Description | | :- | :- | :- | | `21` | Listed | Instrument is listed and not yet open for trading. | | `17` | Open | Instrument is open for trading. | | `2` | Pause | Trading is paused. | | `18` | Closed | Trading is closed. | | `27` | Determined | The outcome is determined. | | `28` | Settled | The instrument is settled. | | `26` | Amended | The instrument was amended. | | `29` | Delisted | The instrument is delisted. | ## BusinessMessageReject (35=j) Sent when an application message cannot be processed: * A `MarketDataRequest` that is structurally malformed, for example a missing required tag or an invalid value format. * Any application message type other than `MarketDataRequest (35=V)`. | Tag | Name | FIX Type | Req | Description | | :- | :- | :- | :- | :- | | 45 | RefSeqNum | SeqNum | N | MsgSeqNum (34) of the rejected message. | | 372 | RefMsgType | String | Y | MsgType (35) of the rejected message. | | 379 | BusinessRejectRefID | String | C | `MDReqID (262)` of a rejected `MarketDataRequest`, when it could be read. | | 380 | BusinessRejectReason | Int | Y | `0` = Other. Sent for every BusinessMessageReject. | | 58 | Text | String | N | Human-readable reason, for example the invalid tag, or `unsupported message type`. | ## Values specific to Coinbase Derivatives: Predictions The gateway uses standard FIX 5.0 SP2 tags. The following values are specific to Coinbase Derivatives: Predictions. | Tag | Value | Description | | :- | :- | :- | | MDEntryType (269) | `L` = Instrument lifecycle | Subscribes to instrument status changes, delivered as [SecurityStatus (35=f)](#securitystatus-35f). | | SecurityTradingStatus (326) | `2`, `17`, `18`, `21`, `26`, `27`, `28`, `29` | Instrument trading statuses with meanings specific to Coinbase Derivatives: Predictions. See [SecurityTradingStatus values](#securitytradingstatus-values). |