FORTUNE lists some of the possible reasons for today's slide:
● Goldman Sachs and Lazard Capital predicting "below consensus guidance" for the June quarter
● A warning by Cirrus Logic, which makes chips for Apple, that its gross margins would go down due to a "decreased forecast for a high volume product."
● A report by Jefferies' Peter Misek suggesting that all three of Apple's anticipated new iPhones -- the iPhone 5S, the low-cost iPhone and the iPhone 6 -- would be delayed.
● Investors rushing out the door just in case Apple's earnings are even lower than expected.
Apple will announce its Q2 FY13 earnings on April 23, 2013.