The iPad has hit a wall

Apple on Tuesday announced its best quarter ever - and the most profitable quarter for any company in history. But that was because of the iPhone. Growth of the iPad, meanwhile, has hit a wall. In fact, the iPad was the only negative aspect of Apple's earnings report.

Based on company data charted for us by BI Intelligence, Apple sold 21.5 million iPad units, which fell below Wall Street expectations and was down 17% year-over-year. Just looking at the chart, it looks like iPad's sales growth peaked in last December, the same quarter Apple launched the iPad Air and iPad mini with Retina display. Apple CEO Tim Cook says there's some cannibalization going on - the iPhone on one side and the Mac on the other - but he also hinted at the iPad having room for growth, particularly in the workplace. "The real opportunity is to bring mobility into the enterprises and change how people work," Cook said on Tuesday's call.

Apple just launched its partnership with IBM last quarter, and the company is expected to launch its first 12-inch iPad, which may offer more features for advanced productivity.