Former Anglo Irish Bank number two Willie McAteer has lost a fortune on his stake in the crippled housebuilder McInerney.
Anglo Irish lent huge sums to the company while Mr McAteer was the bank's finance director.
Shares in McInerney hit new lows last week after reports that it was considering going into examinership.
Sources close to the company described the reports as "speculative".
Mr McAteer holds 170,000 shares in the company, with his family holding another 10,400. His shares were bought in April 2003.
At the peak of the market in February 2007, his stake was worth close to €552,000.
Anglo Irish Bank is a major lender to Barry O'Connor's troubled homebuilding firm.
McInerney owes banks about €236m. It is thought that Anglo and Bank of Ireland may seek a stake in the company as part of a debt-restructuring deal.
McInerney has seen its share price collapse from a high of €3.25 down to just four cent.