Aer Lingus shares increased in value by 10 per cent to €2.40 in the first hour of trading this morning but eased slightly through the day.
The initial IPO values the company at €1.13 billion
The company priced its initial public share offering at €2.20, valuing the airline at around €1.13 billion.
At the close of trading on the ISEQ the share price had slipped slightly to €2.37 up 7.7 per cent.
Speaking on RTÉ radio this morning, Aer Lingus Chief Executive Mr Dermot Mannion described the IPO as "a successful transaction" and insisted two main objectives had been achieved - €400 million in new equity for the purchase of new aircraft and at least €200 million for the Government with a further €300 million in shares expected 'going forward.'
He added that the €400 million would be used to partly-fund the expansion of its short and long-haul fleet.
Mr Mannion denied he was worried that margin traders and hedge funds would target Aer Lingus shares, insisting that 'a lot of effort has been put in over the last few days to ensure that we have a reasonable spread of shareholders."
He added that it was "a broadly-based transaction" and said the company was "not expecting" to be the victim of any such attack.
Aer Lingus issued 208.4 million new shares as part of the offering, while the Government - which held 85 per cent of the airline - has retained a 28 per cent stake on listing.
The Government is expected to sell another 2.8 per cent to the airline's employees over the next few years in order to allow them build their stake back up to 15 per cent. The Government's remaining stake will be worth around €330 million.
The Aer Lingus Employee Share Ownership Trust will hold around 9.9 per cent of the airline at listing, while employees and former employees have agreed to subscribe for some 2.2 per cent of the entire issued share capital.
Around 11.6 per cent will be owned by the public and 40.3 per cent by institutional investors, the Government and Aer Lingus said
Goodbody Stockbrokers Managing Director Roy Barrett revealed this morning the initial public was 3.8 times oversubscribed.
The share price "is at the lower end of the range but at that level demand was very strong," he said.
Some 45 per cent of the total institutional demand came from UK institutions, 20 per cent from Ireland, 20 percent from the rest of the world and around 14 per cent from the United States, Mr Barrett said.
The shares will go on unrestricted sale on Monday.