Financial Information eXchange
The Financial Information eXchange (FIX) protocol is an electronic communications protocol initiated in 1992 for international real-time exchange of information related to securities transactions and markets. With trillions of dollars traded annually on the NASDAQ alone, financial service entities are employing direct market access (DMA) to increase their speed to financial markets.
Source: Wikipedia — Financial Information eXchange (CC BY-SA 4.0)