Apple’s Q4 Earnings Calendar: Do Analysts have Amnesia?

Source: http://www.flickr.com/photos/andrewmalone/

Apple’s (NASDAQ:AAPL) recent quarterly financial reporting fiasco [1] should serve as a reminder to all analysts that even little mistakes can have BIG consequences. Following its Q4 2012 earnings announcement, Apple suffered its worst one-day loss in four years, as a result of the company’s failure to meet Wall Street’s expectations. This was due largely to a simple calendar-generated error – most analysts failed to account for the fact that Apple’s Q4 2012 was one week shorter than the same quarter the year before.

At the root of this error is the 13-week quarter problem. Apple, like many other companies, defines its fiscal quarters in 13-week periods. With the Gregorian calendar, this requires an adjustment (the addition of an extra week every five or six years). Apple added the extra week in 2011, and many Wall Street analysts failed [2] to pick up on the change between 2011 and 2012.

Unfortunately, such analyst errors are all too common. Indeed, on average, analysts tend to…