For many years stock exchanges were physical locations where buyers and sellers met and negotiated. Exchange trading would typically happen on the floor of an exchange, where traders in brightly colored jackets (to identify which firm they worked for) would shout and gesticulate at one another – a process known as open outcry or pit trading (the exchange floors were often pit-shaped – circular, sloping downwards to the centre, so that the traders could see one another). With the improvement in communications technology in the late 20th century, the need for a physical location became less important and traders started to transact from remote locations in what became known as electronic trading.[3] Electronic trading made transactions easier to complete, monitor, clear, and settle and this helped spur on its development.
One of the earliest examples of widespread electronic trading was on Globex, the CME Group’s electronic trading platform conceived in 1987 and launched fully in 1992.[4] This allowed access to a variety of financial markets such as treasuries, foreign exchange and commodities. The Chicago Board of Trade (CBOT) produced a rival system that was based on Oak Trading Systems’ Oak platform branded ‘E Open Outcry,’ an electronic trading platform that allowed for trading to take place alongside that took place in the CBOT pits.
While the majority of retail trading in the United States happens over the Internet, retail trading volumes are dwarfed by institutional, inter-dealer and exchange trading. However, in developing economies, especially in Asia, retail trading constitutes a significant portion of overall trading volume.[citation needed]
For instruments which are not exchange-traded (e.g. US treasury bonds), the inter-dealer market substitutes for the exchange. This is where dealers trade directly with one another or throughinter-dealer brokers (i.e. companies like GFI Group, ICAP and BGC Partners. They acted as middle-men between dealers such as investment banks). This type of trading traditionally took place over the phone but brokers moved to offering electronic trading services instead.
Similarly, B2C trading traditionally happened over the phone and, while some still does, more brokers are allowing their clients to place orders using electronic systems. Many retail (or "discount") brokers (e.g. Charles Schwab, E-Trade) went online during the late 1990s and most retail stock-broking probably takes place over the web now.[3]
Larger institutional clients, however, will generally place electronic orders via proprietary electronic trading platforms such as Bloomberg Terminal, Reuters 3000 Xtra, Thomson Reuters Eikon, BondsPro, Thomson TradeWeb or CanDeal (which connect institutional clients to several dealers), or using their brokers' proprietary software.
For stock trading, the process of connecting counterparties through electronic trading is supported by the Financial Information eXchange (FIX) Protocol. Used by the vast majority of exchanges and traders, the FIX Protocol is the industry standard for pre-trade messaging and trade execution. While the FIX Protocol was developed for trading stocks, it has been further developed to accommodate commodities,[8] foreign exchange,[9] derivatives,[10] and fixed income[11] trading.
Read More : https://en.wikipedia.org/wiki/Stock_exchange