A Reuters survey found that around 10,000 finance jobs would leave Britain or be created overseas in the next several years if the U.K. is not able to join the European single market.
Reuters surveyed 123 banks, asset managers and other financial firms in the U.K. and Europe to learn their plans for dealing with a "hard Brexit."
Frankfurt, Germany, was overwhelmingly the most popular location for the new roles, followed by Paris.
"If it is going to happen it won't be in one big bang," said a senior executive at one of the large banks in Europe that responded to the survey. "There will be a slow drain of jobs from London over a number of years."
Companies were required to submit their Brexit response plans to the Bank of England July 14. However, the Reuters survey found that some firms may be holding off on making decisions in the hopes that current negotiations produce a "softer" Brexit.
More than 100 companies with employees in the U.K. and the European Union recently signed a letter detailing their need for a three-year transitional deal for Brexit, according to the Irish Examiner.