3. Dermot Desmond
Estimated worth: $1 Billion
Dermot Desmond started his career in finance at Citibank, and later worked for the Investment Bank of Ireland and PricewaterhouseCoopers.
In 1981 he founded NCB Stockbrokers, which became Ireland’s largest independent brokerage; he sold it for $39 million in 1994.
With the proceeds, Desmond started his own private equity firm, International Investment & Underwriting.
IIU now has stakes in travel software firm Datalex, Mountain Province Diamonds, Barchester Healthcare and Glasgow soccer club Celtic PLC.