FORTUNE — The value of those 800 million iTunes accounts — most of them attached to credit cards — is starting to have an impact on Apple’s AAPL bottom line.

According to a report in the Wall Street Journal, Apple’s online retail business has passed Staples’ SPLS and Wal-Mart’s WMT digital efforts to occupy a (distant) No. 2 spot after Amazon AMZN .

Part of Apple’s 24% increase last year (to $18.3 billion) is due to an accounting change: For the first time, Apple threw online hardware sales into the mix alongside iTunes and App Store sales.

Source: Asymco
Source: Asymco


Amazon’s retail offerings, of course, are considerably broader than Apple’s. But as Asymco‘s Horace Dediu pointed out in a chart posted on Twitter last week, Apple has the edge in terms of online accounts. Those could come in handy if Apple, as rumored, is working on a new, iOS-based mobile payment service.