Insurance giant Aon plans to move its legal base to Ireland from the UK, in a shift it said was to maintain a "stable corporate structure and capital flexibility" within the European Union.
It is understood the new structure will require some level of approval by the Central Bank of Ireland, although the company moving here will not be a regulated entity itself.
The move does require the approval of Aon shareholders, as well as authorisation from the High Court in England.
With a market capitalisation of $44bn (€39.6bn) and assets in excess of $29bn, Aon will immediately become one of Ireland's biggest companies.
However, it is not shifting jobs to Ireland, and the move will not lead to job losses in London, where Aon will maintain its operating company headquarters, the group said.
After the restructuring, Aon's global parent will be an Irish plc, its operational headquarters will be in London and it will continue to be listed on the New York Stock Exchange.
Aon was founded in Chicago by Irish-American billionaire Patrick Ryan, and is a global insurance broker and professional services firm.
It already has Irish offices, in Dublin and Cork, but is probably best known to many here as a sponsor of Manchester United.
Aon said it had filed a preliminary proxy to move the jurisdiction of incorporation for the firm's parent company to Ireland from the UK.
The Central Bank here said it would not comment on an individual firm, but noted that more than 100 businesses have applied for authorisation to it as a direct result of the Brexit referendum.
Aon said that remaining within the European Union - through its Irish shift - would help the company to maintain a stable corporate structure and capital flexibility.
However, the company said its corporate reorganisation would not result in any material changes to operations.
It said: "Aon will maintain its operating company headquarters in London, and its commitment to the UK and the important London insurance market remains unchanged and unrivalled."
The company anticipates that its move to Ireland will be completed in the first quarter of 2020.