FIX protocol Definition
The Financial Information eXchange (FIX) protocol is an electronic communications protocol developed for international real-time exchange of securities transactions in the finance markets.
A company called FIX Protocol, Ltd. established for this purpose maintains and owns the specification, while keeping it in the public domain.
FIX is used by both the buy side (institutions) as well as the sell side (brokers/dealers) of the financial markets. Among its users are mutual funds such as Putnam Investments as well as large investment banks such as J.P. Morgan or Deutsche Bank Securities. The FIX protocol is also used by the New York Stock Exchange, the Chicago Board Options Exchange and the Australian Stock Exchange.