Wells Fargo & Co.‘s growth in active mobile users appears to have faltered — or maybe not.

For years now, Wells Fargo has kept pace with larger rival JPMorgan Chase in mobile AMU growth, but this quarter, Wells announced today, that its growth was flat, or nearly so — there is considerable ambiguity in the bank’s reporting that makes it hard to precisely tell Wells’s numbers.

Last quarter, Wells said it had “nearly 16 million” mobile users, while this quarter it is “16.0 million.” That certainly represents some growth, but how much? (And shouldn’t investors be provided with that information?) We have reached out to Wells Fargo for more information on this.

It should be noted that this flattening of AMU growth at Wells has appeared, despite the bank’s expansion in consumer checking customers (+5.8% YoY) and small business and business banking checking customers (+5.0% YoY). Even if that “nearly 16 million” is really, say, 15.6 million, the AMU user growth rate would be around half what it is seeing in checking and business customers.

JPMorgan Chase announced its earnings last night, while Wells Fargo and Bank of America announced earnings today.

Chase saw continued strong mobile user growth: 5.7% on the quarter and 20.9% year-over-year. Chase recorded 22.2 million active mobile users last quarter, the most in the nation. Bank of America‘s mobile users increased 4.6% on the quarter and 14.7% year-over-year. B of A counts 18.4 million mobile users, and reported 14% of total deposits through the mobile channel.

No other large bank reports this figure that we are aware of, unless you count PNC, which said today that 45% of deposits came through its self-service channels, ATM, online and mobile.

Chase’s C-level executives still seem a bit bewildered by the mobile success. A year ago CFO Marianne Lake vastly undercounted the bank’s mobile users — she was corrected by Dimon in that instance — and this year she was unable to define the mobile penetration at the bank. It was about 44% last quarter. FDIC data for this quarter is not yet available this quarter, but mobile penetration at Chase has likely grown this quarter.

The chart below shows cumulative mobile user growth at the Big 3 banks. The seasonality is interesting — for the past two years Q3 saw the largest growth, while this year that appears to have shifted to 2Q.

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