Apple Warns of Chip Shortage, Shares Drop 7%

Cook said the problem is not a normal breakdown in the supply chain. "This is not a regular supply issue, it's a demand forecast issue, to be candid," he said, admitting that Apple had underestimated how much customers wanted its newest devices. iPhone sales grew 22 percent and Mac sales grew 25 percent during the quarter. Shortages have already limited how many Mac computers are available, and Apple expects the problem to spread to iPhone and iPad.

Investors were also worried by Apple's forecast for the September quarter. The company expects revenue growth of 9 to 11 percent, below Wall Street's expectation of about 12 percent. The change of mood was sudden: only days earlier Apple had reached a record high and briefly passed a $5 trillion valuation. The earnings call was Cook's last before John Ternus takes over as chief executive on 1 September, leaving his successor to solve the shortages.