Alphabet Inc.¡¯s deeper dive into the U.S. financial system shouldn¡¯t come as much of a surprise. Technology giants have found a way into all corners of people¡¯s lives; the latest plan to offer consumers new forms of bank accounts is simply one of the final frontiers.

The puzzling part of Alphabet¡¯s expansion of Google Pay is why Citigroup Inc. is a willing participant in Silicon Valley¡¯s invasion of Wall Street¡¯s turf.

Last week, Bloomberg News and others reported that Citigroup and a California credit union were Alphabet¡¯s initial partners for a venture that would offer checking accounts through Google Pay.