Apple (Nasdaq: AAPL) shares are plunging in opening minutes of trading in New York.

As of 9:32 a.m. (EDT), Apple stock is down 5.48 percent.

While Apple is expected to release record-breaking quarterly results today after the market closes, investors are worried about the extent of CEO Steve Jobs’ undisclosed illness and the lack of clear plan of succession at the company.

Yesterday, Jobs stated that he was taking a medical leave, but did not indicate the expected duration of his absence. He has a long history of serious health issues.