Co Down native Brian Conlon (52, left) owns 33.
9pc of AIM-listed financial services group First Derivatives. The company performed strongly up until its last set of six months' interim results late last year, with both sales and profits up 20pc. However, the share price has sunk by 49pc in the past year and his stake is now valued at about €208m. Pay and dividends in previous years also add to his wealth. Having started out as a provider of specialist software to leading global investment banks, the firm - which employs over 2,000 people around the world and is one of this island's largest graduate employers - has evolved into a provider of products and consulting services, particularly building on its strength in ultra-high performance data analytics. It now operates in the retail, utilities and digital marketing sectors. Clients include the Red Bull Formula One team and Airbus Defence and Space.