In its results statement Wednesday, JPMorgan Chase reported active online customers of 36.4 million which includes active mobile customers of 19.1 million, up 3.5 million or 22%.

Similar figures are on display at Wells Fargo, which reported 24.8 million active online customers, up eight percent year-over-year, and 14.1 million active mobile customers, up 19% year-over-year.

At Bank of America, the number of mobile banking customers increased 15% from the year-ago quarter to 16.5 million users, and 12% of deposit transactions by customers were done through mobile, compared to nine percent in the comparable period. Since the introduction of Apple Pay in October, nearly 800,000 customers have enrolled in the service, adding approximately 1.1 million cards.

Figures compiled by BI Intelligence in December showed mobile banking customers were 53% of the size of total online banking customers at the three banks.

Desktop-only customers - those that only accessed their accounts on desktop and laptop computers and never on mobile - were 47% of online banking customers during the same time period.

The data shows the switchover in favour of mobile access took place towards the end of Q2 last year.

"We assume that all, or nearly all, mobile banking customers also use desktop banking," states the report. "But if there are many mobile-only online banking customers, then mobile is an even more important banking channel than the chart suggests."

The data tallies with research conducted by Bain and Company among 83,000 consumers in 22 countries last year, which found that banking customers now handle more of their financial interactions, on average, via smartphones and tablets than through any other channel.

The study shows that customers conducted more than 50% of their banking interactions through digital channels in 18 of the 22 countries surveyed. Mobile was found to be the most used banking channel in 13 countries and accounts for around 30% of all interactions worldwide.