Apple's shares swallow biggest loss in four years

From Reuters:
"Apple Inc shares tumbled more than 6 percent on Wednesday, chalking up their biggest single-day loss in four years as fears grow about intensifying competition in the mobile device market."

http://www.reuters.com/article/2012/12/05/us-apple-shares-idUSBRE8B40VK20121205

Basically the sell-off is said to be the result of Apple losing tablet market share due to Android and Windows tablets getting more popular.