Gap fill is not a sure thing. I think at times it may be a self...

Gap fill is not a sure thing. I think at times it may be a self fulfilling prophecy if traders sit on the sidelines until a gap is filled, thereby reducing demand (long position example). Secondly I think algo's could gap hunt in very liquid stocks, if the big funds running those algos have deemed it a valid strategy with whatever rationale they come up with.

Apart from that, I think the assumption of gap-fill is bollocks. Think about it logically, if it were an edge, it would be a popular strategy, in which case everyone would do it, in which case the opportunity would be arbitraged away.

Also think about it intuitively, so are you going to short AO1 and buy back at .004? Your chart says 'gap to be filled'. So that should be an easy 33% short right? LOL.

If you look at charts you will see heaps of unfilled gaps, especially in the penny space.