Thomson Reuters
JP Morgan CEO Jamie Dimon speaks at a Remain in the EU campaign event attended by Britain's Chancellor of the Exchequer George Osborne (not shown) at JP Morgan's corporate centre in Bournemouth
Dimon, speaking on CNBC television during a bus tour of bank offices in California, said it is too early to tell how much of the work the bank now does from the UK might have to be done redundantly in Europe.
The issue is passporting. Right now, EU rules allow banks licensed in one EU country to use that licence to operate in other EU countries, rather than get another approval.
But those rights might be lost post-Brexit. It's too early to tell and the UK will likely make negotiating passporting rights a top priority but who knows what stance EU leaders will take.
If Britain loses passporting rights it's likely that JPMorgan and others will set up a parallel European banking operation somewhere that does still have passporting rights - like Frankfurt or Paris. This operation will get a lot more business.
Dimon has repeatedly warned that JPMorgan may have to move some of its 16,000 UK jobs to continental Europe after Britain surprised the world by voting to leave the EU.
Dimon also said in the CNBC interview that if the next US president makes the right decisions the US economy could grow at a 4% rate.
Dimon was extremely bullish on the US, saying the country has an "unbelievable future" ahead of it.
(Reporting by Sam Forgione and David Henry in New York; Editing by Phil Berlowitz)