The stock was down $50.68, or 9.9 per cent, at $463.32 in late morning trading.
Even with the stock's decline, Apple Inc. is the world's most valuable company, a position it's held for more than a year.
But it's now worth just 4 per cent more than No. 2 Exxon Mobil Corp.
Late Wednesday, Apple reported October-December earnings that were flat compared with the year before.
It predicted sales growth for the current quarter of around 7 per cent —far from the 50-per cent-plus rate it's often hit in recent years.
Analysts believe Apple is unable to fully capitalize on the global smartphone boom with just one new — and very expensive — phone model every year.
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