Around 10,000 finance jobs will be shifted away from the UK in the coming years if the country leaves the single market, a survey has suggested.
Nearly half of the 123 firms polled by Thomson Reuters, among which were banks, insurers, asset managers, private equity firms and exchanges, said they would have to move staff or restructure their businesses due to Brexit.
A third of firms said the UK's exit from the European Union would have no impact on their businesses, while the remainder said they were still making plans.
Reuters said the first wave of expected job losses due to Brexit could be at the lower end of estimates by industry lobby groups and firms, although this could ramp up down the line.
"If it is going to happen it won't be in one big bang," a senior executive at a European bank, who participated in the survey, told Reuters. "There will be a slow drain of jobs from London over a number of years."
The survey also revealed that Frankfurt is the most popular destination for jobs that are likely to be relocated, with Paris coming in second.
The outlook appears particularly bleak for the banking sector, with nearly 9,800 banking roles expected to be affected by Brexit.
A so-called "hard Brexit" would likely mean the loss of passporting rights for British financial institutions, which allow banks based in the UK to offer services to companies and governments across the European Union without restrictions.
Last week, Japan's Mitsubishi UFJ Financial Group confirmed it would shift some jobs from its EU investment banking base in London to Amsterdam due to the uncertainty surrounding Brexit negotiations.
Senior executives who took part in the poll told Reuters that firms would only move a minimal number of jobs away from the UK initially, in order to make sure the necessary infrastructure is in place in their EU branches.
Further restructuring down the line will depend on the details of the final Brexit deal, the prospect for the companies' European business, and whether Frankfurt or other European hubs prove to be viable alternatives to London, they said.