Wikipedia
TradElect was the London Stock Exchange's main electronic trading platform from 2007 to 2011. It ran on Microsoft Windows, using .NET technology and Microsoft SQL Server. Its development took 4 years from project inception to rollout and had a total cost of £40m.
The impetus for the development of TradElect was the rise of algorithmic trading and the liberalisation of the trading sector in Europe due to the Markets in Financial Instruments Directive. Both of these factors meant that stock exchanges - previously facing little or no competition - had to offer faster response times to be competitive. The system which TradElect replaced, Sets, was 10 years old and took 140ms to complete a trade, compared to TradElect's 10ms.
In April 2010 the Oslo Stock Exchange also adopted TradElect, as part of a strategic partnership agreement. The Johannesburg Stock Exchange also adopted TradElect.