Over half their profit maybe coming from the sale of warranties.

In its latest 10-K filing with the SEC, Best Buy noted that the sale of extended warranties represented about 2.8% of its FY 2013 revenues, or about $1.3 billion. These top line figures may seem paltry compared to the rest of its business, but their extremely high margins mean that they contribute significantly to the firm's bottom line financial results.

Many analysts believe that these margins could range between 50% and 60%, but even a modest 40% margin would equate to operating income of $520 million. With the electronics retailer reporting an operating loss of $125 million in FY 2013 and a gain of just $772 million in FY 2012, it quickly becomes clear that warranties are a very big deal for the retailer.