A messy divorce from the European Union would be very expensive for banks in Britain.
Banks would need to raise up to $50 billion to support new operations in Europe if Britain crashes out of the union, according to a new report from the consultancy Oliver Wyman.
There would also be a major hit to jobs. Oliver Wyman estimates that 35,000 to 40,000 banking jobs would be lost over the long run if London is stripped of key businesses as a result of Brexit.
The report is a stark reminder that time is running out for the banks.
Oliver Wyman said the banking industry has spent the past year preparing for Brexit in ways that are not too costly -- for example by applying for licenses in other EU countries.
"Over the next six to 12 months, however, actions will be needed that are more costly and harder to reverse -- such as injecting new capital into EU entities, moving employees, appointing senior management, and building... infrastructure," the report said.
Businesses have pressed Prime Minister Theresa May for more details on her plans for exit talks with the EU, which kicked off in June. Many companies have put investments on hold until there's more clarity.
Yet members of May's cabinet have made contradictory statements on Brexit policy in recent days, adding to the impression of confusion surrounding Britain's goals for Brexit talks.
Treasury chief Philip Hammond said Friday that EU migrants were unlikely to be turned away at the border after March 2019, so long as they register when coming in and out of the country.
But trade boss Liam Fox contradicted him over the weekend, telling the Sunday Times that the free movement of people between Britain and the EU would end with Brexit.
A spokesman for May stepped in on Monday, saying that free movement -- a guiding pillar of the EU -- would end when the U.K. leaves in March 2019.
Oliver Wyman argued that the uncertainty is already taking its toll on the financial industry.
"So long as the outcomes of the Brexit negotiations remain unpredictable, banks must act as if a hard Brexit is coming," the consultancy said in its report. "Some of the fragmentation and inefficiency that would result from a hard Brexit will likely occur even if a closer relationship between the U.K. and EU is ultimately negotiated."
Some banks have already announced they will move jobs away from London because of Brexit.
HSBC is establishing a new European headquarters in Paris, where it will move roughly 1,000 jobs. On Monday, the bank said that legal costs and relocation fees associated with Brexit will cost between $200 million and $300 million.
UBS, Deutsche Bank, Goldman Sachs and JPMorgan have also said they would relocate hundreds of jobs each.
There is evidence that Britain's economy is already slowing.
The U.K. recorded the weakest growth of any European economy in the first three months of the year, and GDP in the second quarter was only half the eurozone's 0.6% rate.
It's a price some are willing to pay.
A survey published by YouGov on Tuesday found that three out of five Brexit voters think that "significant damage to the British economy" is a price worth paying to leave the EU.