Lionel Laurent is a Bloomberg Gadfly columnist covering finance and markets. He previously worked at Reuters and Forbes.

Much has changed since the U.K. voted to leave the EU in June: Pro-Remain politician Theresa May is now a pro-Brexit Prime Minister. Stock-market losses have turned into gains. And bankers who once fretted about the impact on London's future as Europe's pre-eminent financial center are now sounding more optimistic.

Brexit Bounce
The FTSE 100 has recovered from its sharp decline after the June 23 referendum
Source: Bloomberg

Deutsche Bank CEO John Cryan, who in the aftermath of the vote described it as "negative on all sides" and a "bad day for Europe," is now talking up the likelihood London will remain a key financial center -- albeit a very different one.

This is hardly a full-throated cheer, but it still sounds like somebody got May's memo about making the best of Brexit.

How long this warmer tone continues will depend on the government being able to retain the passport rights that give firms based in Britain access to Europe's financial markets.

UBS CEO Sergio Ermotti has said he's hopeful Britain will retain those rights. Last month, Standard Chartered CEO Bill Winters raised the possibility that a deal could be struck that wouldn't impact the square mile. 

This seems a more realistic approach than the dire threats some U.S. firms made before the vote to move several thousand jobs out of the U.K. if the vote went in favor of Brexit.

But these bankers haven't had a full-scale conversion to Brexit on the road to Dusseldorf. It's fairer to say that the pressure to relocate businesses or employees simply isn't there just yet.

The push factors remain entirely theoretical, given the U.K. is dragging its feet on actually starting the exit process. But the cost of moving is very real.

Investment banks have built up glass fortresses in London that would cost a fortune to move. Top banks from outside the EU, among them Morgan Stanley and Credit Suisse, have about $1.8 trillion of assets in their U.K. subsidiaries, according to JPMorgan estimates. About 25 percent of top investment banks' employees are based in Britain, about 45,000 in total.

The Cost of Brexodus
Estimated investment-banking staff based in the U.K.
Source: J.P.Morgan estimates published July 11

 Synechron, a consulting firm, put the cost of moving a single employee at about 50,000 pounds. That implies it would cost more than 2 billion pounds to relocate every employee.

Just as banks owe it to shareholders to examine and disclose all possible material operational and business risks, they also need to weigh the cost of responding to those risks in the wrong way. Want to pay a top consultant -- now re-named "head of Brexit" -- to do some contingency planning? Sure. Want to scope out some real estate in Dublin for two staffers and a Macbook? Absolutely.

But why go further? That could risk angering shareholders, especially if a first-mover loses top talent to less jittery rivals -- and burns through precious cash to boot.

So expect fewer calls for urgent relocation. London's financial industry certainly may look very different in a few years' time. But a Brexodus won't happen until the numbers, and the regulations, add up.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.

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Lionel Laurent in London at

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