The biggest story on Wall Street in recent months has been the plunge in Apple's (NASDAQ: AAPL) share price. The stock, which for a long time only went up, has fallen around 35 percent from all-time high levels above $700 which were hit in September.

The reasons for this have been debated endlessly, but one of the major concerns that investors have pointed to is falling margins for iPhone, which according to Trefis research, accounts for around 55 percent of Apple's valuation. Other reasons for the decline that have been bandied about include weak PC demand hurting Mac sales and dissatisfaction with the iPad Mini price point relative to competitors such as Google's (NASDAQ: GOOG) Nexus 7 and Amazon's Kindle Fire tablets.