The Bank of England is expecting up to 75,000 job losses in the event that there is no deal between the UK and EU financial services sector.
The number is the bank's "reasonable scenario" and originates from an Oliver Wyman report published in 2016.
The estimate applies to the next three-to-five years. The Wyman report estimates up to 40,000 jobs could be lost directly from financial services, and the rest would be lost in the legal and professional services sector.
The bank has been preparing for a possible "no deal" Brexit and has required firms to submit contingency plans for such a scenario.
Lobby groups such as TheCityUK have warned that the EU should not seek to diminish the UK as a financial centre in Brexit talks.
They have argued that the EU would not benefit if it weakens the Square Mile, as jobs would likely move to Singapore and New York rather than European cities such as Frankfurt.
Miles Celic, chief executive of TheCityUK, said, “This is another reminder that a no deal Brexit will be no good for the industry, for customers or the economies of the UK and the EU.
“For our industry, the most urgent priority remains agreeing a time-bound Brexit transition period. EU and UK negotiators must discuss and agree a status quo transitional deal as soon as possible if it is to hold any real value for our industry."