in 2013 BTC become half just because of PANIC SELLING .
i dont think its possible now but if PANIC SELLING continue price will obviously go down.
I did not heard about it. In case it happened again, I will be very happy because that would be a great time a big opportunity for me to buy bitcoins. And I am sure many who believes in bitcoin will do the same. Panic selling is made by people who do not knew bitcoin very well.