jamie dimon
Jamie Dimon, the head of U.S. bank JPMorgan Chase, has told British staff a decision by Britain to leave the European Union could mean "fewer" jobs with the bank there and more jobs in Europe. Mark Wilson/Getty Images

In the aftermath of Britain’s stunning vote to leave the European Union, JPMorgan Chase & Co. and other American banks scrambled Friday to reassess their positions across the pond.

For many U.S. financial firms, the U.K. provides access into the world’s largest integrated market. Losing that entry point could mean a shift in resources from the City of London to financial hubs in Europe.

JPMorgan CEO Jamie Dimon warned earlier this month the bank could lay off as many as 4,000 British employees.

Shares in JPMorgan were down more than 4 percent in trading Friday, compared to a 2 percent loss seen for the S&P 500.

In a memo to employees seen by Business Insider, Dimon Friday laid out the bank’s initial reactions to the referendum and eventual British exit, or Brexit, from the EU. Here are three takeaways from his memo.

Hold Steady — for Now

As British and European regulators begin the arduous and unprecedented process of scrapping a nation’s EU membership, JPMorgan is faced with some tough decisions. But for the time being, the U.K. remains an EU state with the same financial regulations.

“The framework of the U.K.’s engagement with the EU, including trade agreements, will be negotiated over a period of years. For the moment, we will continue to serve our clients as usual, and our operating model in the U.K. remains the same,” Dimon wrote.

But in the months to come, “we may need to make changes to our European legal entity structure and the location of some roles,” Dimon said, without specifying who could be affected or where the bank might move its resources. The bank currently employs 16,000 people in Britain.

Beware the Markets

Financial markets around the world convulsed following the vote, with stock futures from Asia to America sliding by double-digit percentages. The pound sterling fell to its lowest point in three decades.

Dimon sounded a note of confidence amid the clamor: “We recognize the potential for market volatility over the next few weeks and we are ready to help our clients work through it.”

But as trade agreements and financial regulations face reappraisal in the coming months, Dimon warned there could be bad news ahead for clients. “As of today, there are no changes to the structure of our clients’ relationships with JPMorgan Chase or their ability to work with our firm, but again this may change in the coming months or years.”

J.P. Morgan Chase & Co. (JPM) Stock Price | FindTheCompany
A Little Hope

Though the vote to leave the EU is expected to indelibly alter the face of Europe, Dimon suggested the possibility that, for banks at least, the changes could prove manageable.

“We are hopeful that policymakers will recognize the immense value created through a continued open economic engagement between the U.K. and EU members,” Dimon wrote.

As Britain’s Financial Conduct Authority announced after the vote, “the longer term impacts of the decision to leave the EU on the overall regulatory framework for the UK will depend, in part, on the relationship that the U.K. seeks with the EU in the future.”

In other words, it is still possible the two markets maintain close financial ties, with capital freely flowing across the English Channel. But that, like much else in the post-Brexit world, remains uncertain.