After Apple’s Rise, a Bruising Fall - NYTimes.com

tbd if/when Apple's stock price will be directly related to Apple's business results again

"One issue is that Apple is a favorite stock among individual investors. The investment firm SigFig estimated last fall that 17 percent of all retail investors owned Apple stock, four times the number that owns the average stock in the Dow Jones industrial average.
Trading by retail investors can be amplified by hedge funds, who see everyday investors piling in and push in the opposite direction by shorting the stock, betting it will decline. The so-called short interest in Apple reached a peak last November, but hasn’t gone down much since then, according to data from Nasdaq."

After Apple’s Rise, a Bruising Fall - NYTimes.com