A former schoolteacher, Mr Pat McDonagh, has become a dollar billionaire following the spectacular launch yesterday of his company, Riverdeep, on the Irish and US stock exchanges.
His shareholding in the educational software company is now valued at $951 million (£773 million) and, with other investments, his fortune is estimated at $1.025 billion.
Riverdeep's share price increase of 235 per cent on the US Nasdaq exchange yesterday shows the insatiable appetite of investors for technology stocks.
Mr McDonagh (48) holds a 53 per cent stake in Riverdeep, which he founded. It specialises in educational software for US schools. The company has yet to make a profit and has accumulated losses of $32 million.
Following a brief period primary school teaching, and a stint selling encyclopaedias, Mr McDonagh spotted the Internet's potential and in 1983 he founded CBT Systems (now SmartForce), specialising in computer-based training software.
Mr McDonagh made $45 million from the sale of his stake shortly after CBT was floated on the Nasdaq market in 1995. His investments in other technology companies, Rapid Technology - of which he is chairman - and The Bromley Group, are estimated at $26.6 million and $2 million respectively.
Notoriously media-shy, Mr McDonagh prefers to sell his companies' message to investors and was heavily involved in the roadshow pitching Riverdeep at the US investment community.
The company is a direct offshoot of SmartForce and specialises in Internet-based educational programmes for the US school market.
In November Davy Stockbrokers, one of the underwriters of the flotation, took a 14 per cent stake for $15 million. Following post-flotation dilution, this is now estimated to be worth around $162 million.
Mr McDonagh lives in north Dublin and is married with three children. His interests include golf, breeding pedigree cattle and the GAA.