One of Ireland's wealthiest men may have to pay up to €7.6m to Friends First because he gave a personal guarantee to help buy a prestigious hotel in Washington.
The exact amount that must be paid by aviation millionaire Domhnal Slattery (41) will be decided later.
Mr Slattery's private equity firm, Claret Capital, and insurance company Friends First were part of a consortium which bought the St Regis hotel for $180m .
To complete the deal, Friends First loaned money to two Claret Capital-related companies.
The Ailesbury Road resident is the founder of the 'Clare People' newspaper but made his fortune in aviation finance.
His Avolon company has raised $5.1bn to buy a fleet of 167 aircraft which is leased to airlines around the world.
The High Court was told yesterday that the directors of Claret entered into guarantees of a $14.05m loan and also took personal loans from Friends First Finance.
Mr Slattery said he was unaware that one of the documents signed by him was a personal guarantee but later accepted he was bound by a guarantee.
The High Court also ruled, however, that Friends First must pay Mr Slattery €100,000 damages for a "deliberate and conscious breach" of his right to confidentiality.
This breach involved an "extraordinary, wilful and totally inappropriate" revelation of confidential information, Judge Brian McGovern directed.
The damages award arose from Friends First parent company Achmea which revealed details of Mr Slattery's financial dealings to another company called CVC Capital Partners.