> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcus.xyz/llms.txt > Use this file to discover all available pages before exploring further. # Market attributes > > **Endpoint:** `wss://api.arcus.xyz/v1/ws` — one socket multiplexes every channel and RPC request. Click **Connect**, then send the example subscribe message below to start receiving data. Per-market Regular Trading Hours / off-hours attribute state for every online market. 24/7 markets (crypto) are included with `isOutsideRth: false` — they never leave regular trading hours — and every other off-hours field `null`; they never produce streaming updates. Supersedes the `marketAttributes` entry variant on `exchangeAttributeUpdates`. Every entry — snapshot and streaming alike — is the market's COMPLETE current attribute block: `marketId`, `marketDisplayName`, `offHoursInitialMarginFraction`, `isOutsideRth`, `currentSettlementPrice`, both trading-band boundaries and next-level boundaries, and per-side expansion-zone state. Fields that do not currently apply are `null`, never omitted. Field semantics match `GET /v1/markets`. **Global channel — no `id` required.** All subscribers receive the same stream. On subscribe: one full block per online market (`isSnapshot: true`) — a complete bootstrap, no REST read needed. Streaming: a single-entry envelope with the affected market's full post-event block on every RTH boundary crossing, VWAP seal, and off-hours bound event (`isSnapshot: false`). Because each update carries the full block — both sides' bounds, not just the side an event fired on — clients replace their local entry for `marketId` wholesale; `boundEvent` annotates what fired — always present on delta entries (`exitRth` / `enterRth` on RTH boundary crossings, a bound-event name otherwise); `boundSide` is also always present on delta entries (null on RTH-transition / non-bound-event deltas). ## AsyncAPI ````yaml api-reference/asyncapi.yaml marketAttributes id: marketAttributes title: Market attributes description: > > **Endpoint:** `wss://api.arcus.xyz/v1/ws` — one socket multiplexes every channel and RPC request. Click **Connect**, then send the example subscribe message below to start receiving data. Per-market Regular Trading Hours / off-hours attribute state for every online market. 24/7 markets (crypto) are included with `isOutsideRth: false` — they never leave regular trading hours — and every other off-hours field `null`; they never produce streaming updates. Supersedes the `marketAttributes` entry variant on `exchangeAttributeUpdates`. Every entry — snapshot and streaming alike — is the market's COMPLETE current attribute block: `marketId`, `marketDisplayName`, `offHoursInitialMarginFraction`, `isOutsideRth`, `currentSettlementPrice`, both trading-band boundaries and next-level boundaries, and per-side expansion-zone state. Fields that do not currently apply are `null`, never omitted. Field semantics match `GET /v1/markets`. **Global channel — no `id` required.** All subscribers receive the same stream. On subscribe: one full block per online market (`isSnapshot: true`) — a complete bootstrap, no REST read needed. Streaming: a single-entry envelope with the affected market's full post-event block on every RTH boundary crossing, VWAP seal, and off-hours bound event (`isSnapshot: false`). Because each update carries the full block — both sides' bounds, not just the side an event fired on — clients replace their local entry for `marketId` wholesale; `boundEvent` annotates what fired — always present on delta entries (`exitRth` / `enterRth` on RTH boundary crossings, a bound-event name otherwise); `boundSide` is also always present on delta entries (null on RTH-transition / non-bound-event deltas). servers: - id: mainnet protocol: wss host: api.arcus.xyz bindings: [] variables: [] - id: testnet protocol: wss host: api.testnet.arcus.xyz bindings: [] variables: [] address: /v1/ws?channel=marketAttributes parameters: [] bindings: [] operations: - &ref_3 id: subscribeMarketAttributes title: Subscribe market attributes type: receive messages: - &ref_5 id: subscribe contentType: application/json payload: - name: Subscribe to the market attributes channel type: object properties: - name: type type: string description: subscribe required: true - name: channel type: string description: marketAttributes required: true - name: snapshot type: boolean description: >- When false, suppress the initial per-market snapshot on subscribe and stream only live updates. Defaults to true. required: false headers: [] jsonPayloadSchema: type: object required: - type - channel properties: type: type: string const: subscribe x-parser-schema-id: channel: type: string const: marketAttributes x-parser-schema-id: snapshot: type: boolean description: >- When false, suppress the initial per-market snapshot on subscribe and stream only live updates. Defaults to true. default: true x-parser-schema-id: x-parser-schema-id: SubscribeMarketAttributesPayload title: Subscribe to the market attributes channel example: |- { "type": "subscribe", "channel": "marketAttributes" } bindings: [] extensions: - id: x-parser-unique-object-id value: subscribe bindings: [] extensions: &ref_2 - id: x-parser-unique-object-id value: marketAttributes - &ref_4 id: receiveMarketAttributes title: Receive market attributes type: send messages: - &ref_6 id: snapshot contentType: application/json payload: - allOf: &ref_0 - type: object description: Common envelope for all server-pushed channel messages. required: - type - channel properties: type: type: string enum: - subscribed - channel_data description: >- `subscribed` for the initial snapshot; `channel_data` for updates. x-parser-schema-id: channel: type: string description: Channel name. x-parser-schema-id: id: type: string description: >- Channel id (market or address). Absent for global channels. x-parser-schema-id: contents: type: object additionalProperties: true description: Channel-specific payload. Schema varies by channel. properties: {} x-parser-schema-id: x-parser-schema-id: ChannelDataEnvelope - type: object properties: contents: type: object required: - isSnapshot - entries properties: isSnapshot: type: boolean description: > True for the subscribe-time snapshot (one entry per RTH market); false for streaming updates (one entry for the affected market). x-parser-schema-id: entries: type: array items: type: object description: > One market's complete RTH / off-hours attribute block. Every attribute field is present on every entry — `null` when it does not currently apply (in-RTH markets carry null bounds; a side not in its expansion zone carries null zone timestamps). Field semantics match the fields of the same names on `GET /v1/markets`. The `boundEvent` / `boundSide` / `timestamp` / `marketSequenceNum` annotations appear only on streaming updates, never on snapshot entries. required: - marketId - marketDisplayName - offHoursInitialMarginFraction - isOutsideRth - currentSettlementPrice - upperTradingBound - lowerTradingBound - nextUpperTradingBound - nextLowerTradingBound - isUpperInExpansionZone - isLowerInExpansionZone - upperZoneEnteredAt - upperExpectedExpansionAt - lowerZoneEnteredAt - lowerExpectedExpansionAt properties: marketId: type: integer description: Numeric market id. x-parser-schema-id: marketDisplayName: type: string description: Market ticker. example: INTC-USD x-parser-schema-id: offHoursInitialMarginFraction: type: string description: > Initial margin fraction the engine enforces outside the market's RTH window (maintenance margin is not uplifted off-hours). example: '0.2' x-parser-schema-id: isOutsideRth: type: boolean description: > Current Regular Trading Hours state. Always `false` for 24/7 markets (crypto), which never leave regular trading hours. `null` while the server has not yet learned an RTH market's state (briefly after a deploy). nullable: true x-parser-schema-id: currentSettlementPrice: type: string description: > Sealed VWAP settlement price (decimal USD) anchoring the off-hours trading band. `null` in-RTH (no anchor). example: '150.25' nullable: true x-parser-schema-id: upperTradingBound: type: string description: > Actual upper boundary (decimal USD) of the off-hours band: anchor + anchor × initialMarginFraction × bandMultiplier, where the multiplier walks the 0.5×→1×→2×→4× ladder independently per side. `null` in-RTH. example: '165.28' nullable: true x-parser-schema-id: lowerTradingBound: type: string description: >- Actual lower boundary of the off-hours band. `null` in-RTH. example: '135.23' nullable: true x-parser-schema-id: nextUpperTradingBound: type: string description: > Boundary the upper band moves to if it expands one level (equals `upperTradingBound` at the 4× ceiling). `null` in-RTH. example: '180.30' nullable: true x-parser-schema-id: nextLowerTradingBound: type: string description: >- Boundary the lower band moves to if it expands one level. `null` in-RTH. example: '120.20' nullable: true x-parser-schema-id: isUpperInExpansionZone: type: boolean description: > Whether the upper side is in its expansion zone (its 1-hour impact-price EWMA is holding within 90% of the boundary). `null` in-RTH. nullable: true x-parser-schema-id: isLowerInExpansionZone: type: boolean description: >- Whether the lower side is in its expansion zone. `null` in-RTH. nullable: true x-parser-schema-id: upperZoneEnteredAt: type: integer format: int64 description: > Unix seconds the upper side entered its expansion zone. `null` when not in the zone. nullable: true x-parser-schema-id: upperExpectedExpansionAt: type: integer format: int64 description: > Earliest Unix seconds the upper bound can expand (zoneEnteredAt + one hour; not a guarantee — the EWMA must still be in the zone when the hour completes). `null` when not in the zone. nullable: true x-parser-schema-id: lowerZoneEnteredAt: type: integer format: int64 description: >- Unix seconds the lower side entered its expansion zone. `null` when not in the zone. nullable: true x-parser-schema-id: lowerExpectedExpansionAt: type: integer format: int64 description: >- Earliest Unix seconds the lower bound can expand. `null` when not in the zone. nullable: true x-parser-schema-id: boundEvent: type: string enum: - exitRth - enterRth - expansionZoneEntered - expansionZoneExited - tradingBoundExpanded description: > Event annotation for streaming updates. Omitted only on snapshot entries — always present on delta entries, since every update frame is either an RTH transition or a bound event. `exitRth` (market leaves regular trading hours) / `enterRth` (market re-enters) — the block itself carries the resulting state, so there is no separate bound-price field for these. `expansionZoneEntered` (side's impact-price EWMA crossed within 90% of its boundary, starting the 1-hour expansion clock), `expansionZoneExited` (EWMA relaxed out; clock reset), `tradingBoundExpanded` (clock completed; band widened one level on the 0.5×→1×→2×→4× ladder — the new boundary IS the block's `upperTradingBound` / `lowerTradingBound`). x-parser-schema-id: boundSide: type: string enum: - upper - lower description: > Which band edge fired on bound-event deltas ("upper" / "lower"). Null on snapshot entries and on RTH-transition (`exitRth` / `enterRth`) deltas. x-parser-schema-id: timestamp: type: integer format: int64 description: >- Event time in Unix microseconds (streaming updates only). x-parser-schema-id: marketSequenceNum: type: integer format: int64 description: > Per-market transaction sequence number (streaming updates only). Entries emitted by one engine transaction share this value — it identifies the transaction, not the entry, so do not dedup by it alone. x-parser-schema-id: x-parser-schema-id: MarketAttributesEntry x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: x-parser-schema-id: MarketAttributesChannelPayload name: Market Attributes Snapshot description: > Initial snapshot sent once on subscribe: one complete attribute block per online market, 24/7 crypto included (`isSnapshot: true`). Every field is present on every entry — `null` when it does not currently apply — so no REST bootstrap is needed. headers: [] jsonPayloadSchema: &ref_1 allOf: *ref_0 x-parser-schema-id: MarketAttributesChannelPayload title: Market Attributes Snapshot description: > Initial snapshot sent once on subscribe: one complete attribute block per online market, 24/7 crypto included (`isSnapshot: true`). Every field is present on every entry — `null` when it does not currently apply — so no REST bootstrap is needed. example: |- { "type": "subscribed", "channel": "marketAttributes", "id": "", "contents": { "isSnapshot": true, "entries": [ { "marketId": 0, "marketDisplayName": "BTC-USD", "offHoursInitialMarginFraction": "0.05", "isOutsideRth": false, "currentSettlementPrice": null, "upperTradingBound": null, "lowerTradingBound": null, "nextUpperTradingBound": null, "nextLowerTradingBound": null, "isUpperInExpansionZone": null, "isLowerInExpansionZone": null, "upperZoneEnteredAt": null, "upperExpectedExpansionAt": null, "lowerZoneEnteredAt": null, "lowerExpectedExpansionAt": null }, { "marketId": 12, "marketDisplayName": "INTC-USD", "offHoursInitialMarginFraction": "0.2", "isOutsideRth": true, "currentSettlementPrice": "150.25", "upperTradingBound": "165.28", "lowerTradingBound": "135.23", "nextUpperTradingBound": "180.30", "nextLowerTradingBound": "120.20", "isUpperInExpansionZone": false, "isLowerInExpansionZone": false, "upperZoneEnteredAt": null, "upperExpectedExpansionAt": null, "lowerZoneEnteredAt": null, "lowerExpectedExpansionAt": null }, { "marketId": 15, "marketDisplayName": "TSLA-USD", "offHoursInitialMarginFraction": "0.2", "isOutsideRth": false, "currentSettlementPrice": null, "upperTradingBound": null, "lowerTradingBound": null, "nextUpperTradingBound": null, "nextLowerTradingBound": null, "isUpperInExpansionZone": null, "isLowerInExpansionZone": null, "upperZoneEnteredAt": null, "upperExpectedExpansionAt": null, "lowerZoneEnteredAt": null, "lowerExpectedExpansionAt": null } ] } } bindings: [] extensions: - id: x-parser-unique-object-id value: snapshot - &ref_7 id: update contentType: application/json payload: - allOf: *ref_0 x-parser-schema-id: MarketAttributesChannelPayload name: Market Attributes Update description: > Streaming update pushed on every RTH boundary crossing, VWAP seal, and off-hours bound event. The single entry is the affected market's full post-event attribute block — both sides' bounds, not just the side an event fired on — so clients replace their local entry for `marketId` wholesale. `boundEvent` annotates what fired — always present on delta entries (`exitRth` / `enterRth` on RTH boundary crossings, a bound-event name otherwise); `boundSide` is also always present on delta entries (null on RTH-transition / non-bound-event deltas). headers: [] jsonPayloadSchema: *ref_1 title: Market Attributes Update description: > Streaming update pushed on every RTH boundary crossing, VWAP seal, and off-hours bound event. The single entry is the affected market's full post-event attribute block — both sides' bounds, not just the side an event fired on — so clients replace their local entry for `marketId` wholesale. `boundEvent` annotates what fired — always present on delta entries (`exitRth` / `enterRth` on RTH boundary crossings, a bound-event name otherwise); `boundSide` is also always present on delta entries (null on RTH-transition / non-bound-event deltas). example: |- { "type": "channel_data", "channel": "marketAttributes", "id": "", "contents": { "isSnapshot": false, "entries": [ { "marketId": 12, "marketDisplayName": "INTC-USD", "offHoursInitialMarginFraction": "0.2", "isOutsideRth": true, "currentSettlementPrice": "150.25", "upperTradingBound": "180.30", "lowerTradingBound": "135.23", "nextUpperTradingBound": "210.35", "nextLowerTradingBound": "120.20", "isUpperInExpansionZone": false, "isLowerInExpansionZone": false, "upperZoneEnteredAt": null, "upperExpectedExpansionAt": null, "lowerZoneEnteredAt": null, "lowerExpectedExpansionAt": null, "boundEvent": "tradingBoundExpanded", "boundSide": "upper", "timestamp": 1753822800000000, "marketSequenceNum": 4211 } ] } } bindings: [] extensions: - id: x-parser-unique-object-id value: update bindings: [] extensions: *ref_2 sendOperations: - *ref_3 receiveOperations: - *ref_4 sendMessages: - *ref_5 receiveMessages: - *ref_6 - *ref_7 extensions: - id: x-parser-unique-object-id value: marketAttributes securitySchemes: [] ````