BitMEX WebSocket API adds new “pool” field for protected order books (19 May 2026)

Published: 2026-05-12 08:06:09 |

BitMEX announced an update to its WebSocket API subscription responses. From 19 May 2026 (06:00–09:00 UTC), a new field named “pool” will be added to responses for key feeds: orderBookL2, orderBookL2_25, orderBookL2_100, orderBook10, quote, quoteBin1m/5m/1h/1d, trade, and tradeBin1m/5m/1h/1d. The field will be populated in the BitMEX WebSocket API subscription response. In BitMEX WebSocket API, “pool” indicates which liquidity pool a subscription belongs to. BitMEX says this change is required to support “protected order books,” aiming for tighter spreads and deeper liquidity for a subset of traders. The change is additive, so existing fields remain and most integrations should be unaffected. Availability: BitMEX Testnet will support the update starting 13 May 2026 (06:00–09:00 UTC). Key trading impact for users is primarily technical: trading systems that parse WebSocket subscription payloads may need to accommodate the new “pool” field when building or updating market-data ingestion for order book and trade streams.

Neutral

This is a technical, additive change to BitMEX WebSocket API market-data payloads. It introduces a new “pool” field to support protected order books, which may improve spreads and liquidity for a subset of traders. However, because the change does not remove existing fields and is expected to leave most integrations unaffected, it is unlikely to meaningfully disrupt overall market structure or volatility. Short-term, traders running automated market-data pipelines may see minor breakage risk if parsers are strict and fail on unexpected fields; once updated, the impact should be minimal. Order-book consumers that begin segment-aware analysis could notice slightly different depth/spread characteristics in the protected pool, but that is more about data interpretation than broad price discovery. Long-term, if protected order books consistently deliver tighter spreads and deeper liquidity for targeted flows, it could marginally shift order placement behavior and improve microstructure in those segments. Still, absent changes to listing, fees, leverage, or risk controls, the broader market impact should remain limited—hence a neutral assessment. Similar historical exchange API/versioning updates typically cause short-lived operational noise rather than sustained bull/bear repricing.