Bank of Ireland Chief Executive boss Richie Boucher has said he would have been "astounded" if he was not asked to appear at the Banking Inquiry.
"We deeply regret what happened," he said.
He said the bank was naive about what was happening in its competitors.
"We are transparent about what mistakes we made," he said.
"The mistake we made was coming into a downturn with too little capital."
He said the bank had also been too dependent on wholesale capital and there were "flaws" in the bank's understanding of risk.
"What went wrong? Why did it go wrong? These are the questions we are asked by investors" he said.
Mr Boucher was speaking as BOI reported a pre-tax profit of €920m for last year compared to a loss of over €500m the previous year.
Mr Boucher said BOI is well placed to benefit from economic recovery in Ireland.
He said all the bank's divisions were profitable last year and that it had seen a significant fall in the number of customers in arrears and those who were defaulting on their debts.
The Banking Inquiry has asked for a range of documents and the bank has submitted 6,000 documents.
Former Bank of Ireland figures appearing before the inquiry will also be entitled to see the documents.