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FIX Protocol
syn. FIX / FIX 4.4 / FIX 5.0
Financial Information eXchange — an industry-standard messaging protocol used for real-time electronic communication of trade orders and execution between brokers, LPs, and exchanges.
Last updated: February 10, 2026
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FIX uses a tag-value pair messaging format (e.g., Tag 35=D for New Order Single).
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Brokers and LPs establish FIX sessions over TCP connections with heartbeat monitoring.
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Order messages flow from broker to LP; execution reports flow back.
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Market data can also be distributed via FIX (Market Data Request/Full Refresh).
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The protocol supports order lifecycle events: new, replace, cancel, fill, reject.