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.
This.
There are way too many people investing in bitcoin all over the globe. We cannot say how two persons' action in selling off all of their bitcoin affect the global market as a whole because we do not know how much their bitcoin is. While a certain amount would probably just move the price a bit, it can also be counterbalanced by others buying of bitcoin. What would cause a huge dip in the market would be selling of a lot of bitcoin.