J.P. Morgan Chase & Co. is quietly testing technology that underpins the digital currency bitcoin on U.S. dollar transfers between London and Tokyo, part of an effort to boost its spending to deal with emerging threats from Silicon Valley.

The nation’s largest bank has been testing the program in recent months to move U.S. dollars for about 2,200 clients between the two financial centers using a version of the “blockchain” technology that underpins bitcoin, said Daniel Pinto, head of J.P. Morgan’s corporate and investment...