It's been an anxious few days in the UK following the shock result of the EU referendum with major firms warning that jobs might have to moved overseas.
The crux of the issue for many companies is what sort of access the country will have to Europe's single market. This is something that might be politically impossible after Thursday's vote as it comes with the requirement of the freedom of movement of people.
The added problem for London's financial heart is whether it retains rights to "passport" its services to the rest of the European Union, which effectively allows it to carry on permitted activities in the wider European Economic Area (EEA). CNBC highlights the companies that have already signaled what could lie ahead:
The telecoms giant has its group headquarters in London and stated the importance of the UK membership of the EU on Tuesday.
In an emailed statement it said that it was not yet possible to draw any firm conclusions regarding the long-term location for the headquarters but added that it "will continue to evaluate the situation" and will take whatever decisions are appropriate.
The co-chief executive of the international branch of the US investment bank has said that some of the bank's 6,500 staff in the UK may be moved, according to a report in The Times.
Richard Gnodde of Goldman Sachs, said at a CEO summit that "every outcome is possible" when asked about relocating staff following the referendum results.
Carolyn McCall, the chief executive of European budget carrier easyJet, told Channel 4 News on Tuesday that it "remains to be seen" whether it would move its headquarters to somewhere like Dublin or Paris.
"We have to think of all the scenarios," she told the news broadcaster on a visit to Brussels.
Within hours of the referendum results, Jamie Dimon, the chairman and CEO of JPMorgan, sent a message to employees which was posted online by Business Insider.
"In the months ahead ... we may need to make changes to our European legal entity structure and the location of some roles. While these changes are not certain, we have to be prepared to comply with new laws as we serve our clients around the world," he said, according to the transcript.
EBA (European Banking Authority)
The independent EU financial regulator, based in London, might find itself looking for a new home but says any decisions regarding its possible relocation will have to be discussed at EU level.
"In the meantime, the EBA will continue to fulfil its responsibilities and continue to work towards the achievement of a consistent and transparent functioning of the single market for the entire EU banking system," a spokesperson told CNBC via email.
The international banking giant said in February that it may move some jobs depending on the outcome of the "passporting" rules.