The FIX protocol is widely used across all asset classes, and supported by most markets.
It is the workhorse of communications between modern trading systems. FIX forms the backbone of communication between buy-side firms, sell-side brokers, market-makers, exchanges, ECNs, market data providers, and anyone participating in electronic trading. Even in areas where it has been superseded by other trading protocols, FIX often remains the de facto model for many of its replacements. For example, many equities exchanges offer binary order-entry interfaces as alternatives to FIX, but most of those binary protocols are modeled more or less directly on FIX. Examples include BOE’s BATS Binary Order Entry and ICE’s NYSE Pillar.