Apple's stock is not having a good day as investors are punishing the company for performing worse than expectations. Don't get me wrong, they had an incredible quarter--just like always--but it was below analyst expectations in some regards. Furthermore, investors are worried about the supply shortage that Apple has been experiencing in regards to the iPhone and iPad mini.
The stock has since recovered from the low point seen above, but it is still in the low $600s. This is the first time that Apple stock has been below $600 since July. The fact that iPhones are still in a "significant state of backlog" is casting fears that it could impact sales, though Tim Cook disagrees.
The iPad mini went up for preorder this morning and had already sold out of some models and subsequently pushed shipping time back. Tim Cook says he is "pleased with the current volume of output" and believes that the component shortages would not hold back sales. However, he expects the new iMac to be significantly constrained for the next quarter.