Gardaí in Dublin have been given a further 12 hours to question William McAteer, a former Finance Director of Anglo Irish Bank.
He is the second senior figure from the institution to be arrested as part of a garda investigation into financial irregularities.
Mr McAteer was arrested at his home at 6.30am this morning.
The 59-year-old is being detained under Section 4 of the Criminal Justice Act 1984 at Irishtown Garda Station.
It was Mr McAteer's job to know all about Anglo Irish Bank's finances - how much it borrowed, how much it loaned and how much it had on deposit.
Mr McAteer was in that position when two of the activities gardaí are now investigating occurred: the Anglo Irish Share Support Scheme whereby the bank lent its money to a 'golden circle' of customers to buy its shares in July 2008 and the transfer of over €7.5bn to Anglo from Irish Life & Permanent in September 2008.
He resigned in January 2009 after secret loans of over €100m to the bank's directors emerged.
He has also been held in connection with offences under Section 10 of the Theft and Fraud Offences Act.
Speaking on RTÉ's Morning Ireland, Chairman Designate of Anglo Irish Bank Alan Dukes said the sooner the investigations at the bank are brought to a conclusion the better.
Minister for Finance Brian Lenihan has said that justice has to take its course in relation to the ongoing investigation.
