Without a doubt this is a short squeeze. With 5.7M short shares out there before today, 4.4M shares traded so far. normal volume is 1.4M. Obvious what happened.
Question is, once shorts are done, where does ULTA go? Personally, I am not sure. It may remain flat.
5.2M shares traded, that is almost the entire # of shares short coming into today. Of course more shorts have come in since.
New shorts will come in. It has to pullback. Unless Ulta wants to buyback at 100, a pullback to the lower 90's will give a decent entry point. Even Stern Agee has them with a price target of $100. How much further will it run?