All the time. It comes when there are rumors of deals or buyouts or approvals. Investors rush in blind to try and hit it rich and as the stock goes up, smarter folks are selling into it ... much like auction fever. AUPH has had such rumors for many years now.

 

Look at the open today. The rumor was out and you can see a micro example of what you are talking about at the end of the day. I believe I saw the rumors before the open and, sure enough, once the market opened, in came the get rich quick crowd. Then it became a game of musical chairs and the last guy standing was the "Chump".

 

The trick there is to buy the selloff when the volume died, between 11 and 11:30. Until a rumor is discounted, it will almost always start up again and have a 2nd run and that is what AUPH did today.