Some funds dumped the stock last year to take advantage of the lower taxes.
On top of that GS sold AAPL notes to bunch hedge funds and some naive investors which would expires worthless if AAPL stays below 500-520.
The vicious attacks by CNBC and bad publicity scared new investors and scared old investors.
There is no reason to be concern in the long term because AAPL hasn't been as strong financially and technologically. For the moment is not the "IT" stock but soon big funds will come back to their senses .
I personally think AAPL will be around 550 in 3 months.