Liberty Specialty Markets, one of the five largest members of Lloyd's of London, has picked Luxembourg for its EU base according to reports.
However, Liberty Specialty, which is owned by US giant Liberty Mutual, said it is still examining its options.
A spokesperson for the firm said: "Liberty Specialty Markets is continuing to analyse a number of options, in terms of structure and jurisdiction, in order to be able to offer a company and Lloyd's solution for trading in and from Europe post-Brexit. We expect to give more information in June but, as yet, no decisions have been taken."
Luxembourg was also recently selected by US giant AIG as its post-Brexit EU base.
But the Grand Duchy narrowly missed out to the Lloyd's of London corporation, which selected Brussels.
Financial services firms are mulling their options in order to sell certain products to EU clients. Insurers are looking to head off the impact of Britain's exit from the EU by setting up offices on the continent.
Hiscox said it expects its Luxembourg base to employ around 10 people, primarily tasked with compliance and risk roles. Underwriting functions for European business will remain in local jurisdictions.
Meanwhile, Lloyd's of London said it anticipates the number of people employed in its Brussels offices to be "in the 10s". Around 11 per cent of the corporation's business comes from the EU, but it said it expects half would still be written from the UK.