Shares in AIB closed higher in Dublin today in their full market debut after the Government sold a 25% stake in a €3 billion listing.
The bank's shares ended the day at €4.72, around 7% above the initial public offering (IPO) price of €4.40.
Shares also began trading in London where the deal was the biggest IPO by market capitalisation in almost six years.
The size of the IPO will rise to 28.75% if demand proves strong following the debut, after the Government included an over-allotment, option. The increase would add another €400m to state coffers.
AIB's Chief Executive Bernard Byrne rang the ceremonial bell at the Irish Stock Exchange to mark the occasion.
Speaking on Morning Ireland, Mr Byrne said the whole flotation process over the last few months gave AIB an opportunity to meet with a very wide range of investors.
A significant number of these were able to receive a positive allocation through the whole process, he added.
"We are very comfortable that we have a good shareholder base at this stage which is very solid and very interested in supporting AIB, understanding the Irish economy and is there for the long haul," Mr Byrne stated.
He said the investors who had taken a stake in the bank are taking a long term view of both the Irish market and the Irish economy and are very positively supporting it.
Up to last week's flotation, the AIB CEO said the bank had been following a very commercial agenda, and he said that will remain the basis for the bank in the future.
He added that AIB's investors thought about that strategy and were comfortable that the bank - and its board - would follow it.
While more than 70% of AIB remains in the hands of the State, Mr Byrne said the IPO process had shown there is huge investor appetite for Ireland and for AIB.
He said the Government last week saw that there is massive support for AIB in the market place, adding that it is their decision when to sell off more shares in the bank.
Mr Bryne said the State is in a much better position to capitalise on and realise its investment in AIB over the timeframe it picks.