Fidessa group Holdings Ltd (formerly Fidessa Group Plc), is a British-headquartered company which provides financial markets software and services, such as trading and investment management systems, analytics and market data, to buy side and sell side clients in the financial services sector.

It was listed on the London Stock Exchange and was a member of the FTSE 250 Index before it was acquired by ION Investment Group, which also owns financial content provider Dealogic and financial media group Acuris.

The following day, Fidessa's board recommended that shareholders accept an offer of £35.67 per share to purchase the company, valuing it at £1.4 billion.

[8] In addition to a trading platform, Fidessa hosts a broker neutral FIX-enabled execution network.

This has a large number of brokers connected to it and is similar to other inhouse FIX networks, such as the LSE Hub, the SunGard Transaction Network (STN) and Thomson Reuters subsidiary TradeWeb's Autex Trade Route.