The company's shares fell US$16.79, or 10.1 percent, in after-market trading of Nasdaq stocks.
The spill came after the company reported solid earnings for its fiscal third quarter, which ended June 28. Apple's net income came in at $1.07 billion, which beat analyst estimates of $976 million, according to analysts polled by Thomson Financial. Apple's revenue also beat expectations, at $7.46 billion, versus estimates of $7.37 billion.
What hurt the company's stock in the after-market was its forecast for weaker than expected earnings and revenue growth in its current quarter.
Apple forecast fourth quarter net income of $1.00 per share on revenue of $7.8 billion, lagging analysts' estimates in both cases. Although Apple is known to be conservative when forecasting ahead, uncertainty around the state of the global economy and demand for handsets, computers and other gadgets hurt sentiment on Apple's stock.
Concerns about Steve Jobs' health also weighed on the shares. The health of the popular executive has been discussed widely since he had a tumor removed from his pancreas in 2004. Most recently, the health concern was raised when he appeared on stage looking gaunt at the Worldwide Developer's Conference in June.
On Monday, the New York Post ran a report raising the health issue again.
When asked about Jobs, who did not attend the analyst Web cast, Apple executives side-stepped the question.
"Steve's health is a private matter," said Tim Cook, Apple's chief operating officer, adding that Jobs has no plans to leave Apple.