2 things to consider
Lets say merger info hits and that 3mill is owned by 1 or 2 people who have no other interest in the stock. They could panic, and sell, which, depending on the volume for the day, might be nothing more than a blip on the screen, or it might cause some upward movement. Or they might let it have its little run and win when it crashes again.
Lets say merger info hits and that 3 mill is owned by 1 or 2 people who have large long holdings as well. They are shorting it to hedge against possible problems, and so when the run happens, they ride it out, sell their large long holdings, and ride the shorts back down.
There is a final thing to consider, which I know noone here wants to listen to, and that is that someone knows how much poo is being shoveled, and has just chucked 300k worth of margin (which even at margin interest rates is not that big of a hit) into a pinkie they know will be dead to the .001's again within 6-12 months.