You would get a clearer answer if you specify the amount of bitcoin which are going to be sold. "Huge" can be anywhere from 1000BTC to 1MBTC. The former won't even move the market while the latter will likely result in a substantial drop on the price.
I agree. In addition, the volume of the market at the dump time is also so important. The buy reflex of the buyers is another parameter which can influence the fall. Another parameter is the power of second and third sell wave. I hope this situation will never happen.