The London Stock Exchange is the most important exchange in Europe, it has over 3,000 companies listed on it and is the most international with 350 companies from different parts of the world.
The London Stock Exchanges main trading system is called the Stock Exchange Electronic Trading Service or as people in finance know it as (SETS). It is an automated system that is order driven- this means that when a buy and sell price match an order is executed.
The LSE also has other systems such as Stock Exchange Electronic Trading Service-quotes and crosses (SETSqx) for shares that don't have sufficient liquidity. This uses periodic auctions with quotes from market makers and it is a quote driven system
The LSE also has the Stock Exchange Automated Quotation (SEAQ) which trades fixed interest shares and AIM shares-a sub-market of the London Stock Exchange, allowing smaller companies to float shares with a more flexible regulatory system than is applicable to the main market.
The New York Stock Exchange (NYSE), which is operated by NYSE Euronext is one of the if not the largest stock exchange as measured by its market capitalisation and the value of shares traded on it.
The NYSE uses a continuous auction format, firms which are members of the NYSE act as auctioneers in an open outcry auction market, but most of the orders are delivered electronically and it is a mix of open outcry and electronic trading.
NYSE Euronext is a cross border exchange that operates equities, bond and derivative markets in Belgium, France, Portugal,Neatherlands and the United Kingdom (derivatives only). NYSE Euronext is an order driven market. Intercontinental Exchange (ICE) now owns NYSE Euronext