Pat Neary, the former Financial Regulator has described the disclosure in March 2008 of Sean Quinn's large stake in Anglo Irish Bank as 'very worrying'.
Willie McAteer, Pat Whelan and the former Anglo Chairman Sean FitzPatrick are accused of unlawfully providing funding for the purchase of the bank's shares in July that year.
Neary has described as 'unusual' a request from Anglo's then chief executive David Drumm for a meeting in person in 2007.
He said Mr Drumm was concerned about market rumours that Cavan businessman Sean Quinn had built up a 10% stake in Anglo using a financial instrument called Contracts for Difference.
He also described a second meeting this time with Sean Quinn who come in for a courtesy visit in early 2008 and told the regulator how strong the Quinn group was.
He said Mr Quinn told him he had a small CFD position in Anglo and Ryanair that he planned to dispose of.
Mr Neary added in March that year he learned the true scale of Sean Quinn's holdings in Anglo was 28.4%, he said it was a serious disclosure and a very worrying one.
He has not yet given evidence about the allegedly illegal loans for shares transaction undertaken in July to unwind Mr Quinn's stake in the bank.