Sir Anthony O'Reilly no longer has a notifiable stake in Providence Resources - just one year after he owned 15.5pc of the oil and gas explorer run by his son.
Providence declined to comment on a transaction last week that means O'Reilly's stake in the company is less than 3pc. He won't have to disclose future share sales to the stock exchange.
O'Reilly's shareholding has declined steadily since the start of the year, amid a legal battle with AIB over debts.
After the company - run by O'Reilly's son Tony - raised $28m at the end of March, O'Reilly's stake was reduced further.
Earlier this month AIB was accused of trying to "humiliate and embarrass" O'Reilly after asking him to swear a further statement outlining his assets and liabilities.
O'Reilly's counsel Bernard Dunleavy told the Commercial Court that the the bank's application was "disreputable". AIB's lawyer James Doherty rejected that contention, saying the application was designed to clarify O'Reilly's "complex" financial affairs.
Sunday Indo Business