I don't understand how pointing out an obvious algo trader is paranoia. I was watching today when 108K shares popped up on the ask and then went away as rapidly as they came up with no corresponding sales. The fight was in the 4.48-4.54 range AFTER it had already crossed resistance once. 94-108K shares on and off consistently for several minutes. The shares were not due to resistance....they were fake shares posted to slow the momentum down. If you keep your eye on level II, you can see when they make the moves. The big blocks at 4.71 and 4.72 were there well before the stock got there and were legit big blocks. That would be the next resistance line for me...and I think you are right that 4.50 will probably be support.