The former chief financial officer of Anglo Irish Bank has finished his evidence in the trial of the bank's former chairman and two former directors.
Seán FitzPatrick, Patrick Whelan and William McAteer deny giving unlawful loans to 16 people to buy shares in the bank.
Mr Whelan also denies seven charges of being involved in fraudulently altering documents.
Matt Moran agreed there was "plausible deniability" about the Financial Regulator's attitude towards a proposed deal to reduce Seán Quinn's interest in the bank.
The bank first attempted to finalise this deal in March 2008. It planned to lend money to the Quinn family to buy a portion of Anglo shares outright and sell the rest to other investors.
Mr Moran said it was his understanding that the bank was not getting approval from the regulator, but getting no objection.
He agreed the regulator was putting significant pressure on the bank to get a deal done to reduce Mr Quinn's interest in the bank.
Mr Moran said if Mr Quinn's position had been unwound in a disorderly way, it could have had a calamitous effect on the bank and the whole financial system.
He said executives from Morgan Stanley, the global firm that was to carry out the deal, asked why the regulator was so keen to get the deal done and said it appeared to be rushed.
Mr Moran said there was huge disappointment expressed by the regulator's office when investors could not be found to buy some of the shares in which Mr Quinn had an interest.
He said his boss, Mr McAteer, told Con Horan from the regulator's office that the bank could not ignore the advice of Morgan Stanley in March and April that the market was too fragile to look for investors to buy shares.
Mr Moran confirmed again that Mr Horan asked for references to the regulator to be removed from a draft agreement between the Quinns and Anglo.
He agreed with senior counsel for Mr FitzPatrick, Michael O'Higgins, that "plausible deniability" meant being involved in something, controlling it in some shape or form, but not appearing above the waterline so that if questions were raised later, you could say you were not involved in a plausible way.
Mr Moran said that appeared to be what happened in this case.
Mr Moran said the first he knew about the new plan to ask ten customers of the bank to buy some of the shares in which Mr Quinn had an interest was in July 2008, when he got an email from the bank's former chief executive David Drumm.
The email in which Mr Drumm said it was "time for action" was described as a call to arms.
Mr Moran said the plan was a "last roll of dice" and the "last chance saloon".
The trial has been adjourned. The jury have been told to return on Wednesday morning when evidence is expected to resume.