FIX Protocol
The Financial Information eXchange (FIX) protocol is an open messaging standard for the electronic communication of trade-related information between financial institutions, enabling standardised order submission, execution reporting, and confirmation across brokers, exchanges, and investment managers globally.
FIX Protocol originated in 1992 as a bilateral electronic messaging standard agreed between Fidelity Investments and Salomon Brothers to automate the exchange of equity order information. It has since evolved into the dominant communication standard for institutional trading globally, maintained by the non-profit FIX Trading Community, whose members include major exchanges, brokers, asset managers, and technology vendors.
The protocol defines a set of message types — each with a numeric tag identifying the message type and a series of tag-value pairs carrying the content — that cover the complete trade lifecycle. FIX NewOrderSingle (message type 35=D) carries the initial order from a client to a broker. ExecutionReport (35=8) carries fills, partial fills, cancellation confirmations, and order status updates back from the broker to the client. OrderCancelRequest (35=F) and OrderCancelReplaceRequest (35=G) handle order modification. Allocation messages handle post-trade distribution of fills across multiple portfolios.
In India, NSE provided a FIX-based interface for members seeking to connect external order management or execution systems to exchange infrastructure. This made it possible for institutional investors using globally standardised OMS and EMS platforms to route orders to Indian exchanges without bespoke connectivity development. The FIX interface complemented the proprietary NEAT (National Exchange for Automated Trading) protocol used by broker trading terminals.
FIX Protocol versions have evolved significantly over the years. FIX 4.2 and 4.4 remain widely deployed because of the enormous installed base of systems built on these versions. FIX 5.0 introduced more extensive support for new asset classes and workflow scenarios. FIXML is an XML-based variant offering richer data structuring. More recently, the FIX Trading Community developed FIXP (FIX Performance) and SBE (Simple Binary Encoding) as high-performance binary alternatives optimised for low-latency environments where the overhead of text-based FIX parsing is unacceptable.
For co-located algorithmic trading at NSE, where round-trip latency is measured in microseconds, native binary protocols typically offer lower latency than FIX. However, FIX remains important for the connectivity between institutional investors, custodians, and their executing brokers — a workflow where the volume of messages is lower and the richness of the workflow (allocation, confirmation, affirmation) is more important than raw speed.
Understanding FIX Protocol is essentially a prerequisite for any technology professional working in institutional equity trading infrastructure, regardless of geography.