Misys plc (LSE: MSY) is a British multinational software company headquartered in London. It specialises in software for banking and investment businesses. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index.

The company was founded in 1979 as a computer systems supplier to UK insurance brokers.

The company started in the late 1970s under the name of BIS Ltd and in 1976 acquired Kingsley-Smith and Associates and a software package named MIDAS. This banking software system was based on a concept of a core multi-currency accounting module. At the time all other International Banks worldwide worked and accounted on a 'single currency' methodology. It was marketed to and operated successfully by a number of client London Banks from 1979. From the mid to late-1980s lesser competition to MIDAS came from two other separate software vendors with systems called Kapiti and IBIS. BIS/Misys in acquiring 'Kapiti' as a strategic purchase raised MIDAS to the market leader for 'off-the'shelf' banking software.