Sales of its high-density servers and racks to huge customers have been the bread and butter for Rackable (RACK), as Microsoft (MSFT) and Yahoo (YHOO) have historically accounted for about 60 percent of the company's sales. Last quarter analysts noted that sales to Amazon (AMZN) were helping Rackable's results, as the retailer buys hardware to support its utility computing platform.
In the latest quarterly earnings call, Rackable said it has added a fourth large customer, as Facebook is now among its top accounts. That relationship positions Rackable to benefit as Facebook beefs up its infrastructure in coming months. Facebook recently leased additional data center space from DuPont Fabros, and has cash to invest in the wake of fresh investment from Microsoft and venture capital firms. Facebook had 30.6 million visitors in September, according to data from comScore.