sure there is shorting otherwise we would be so up like a rocket to the moon, there is not enuf shares when a whale bites so the MMs job is to supply shares, they are doing their jobs but it sure is fun watchin them work it.
Unless you mean some crazy short term alogrithm, i.e. holding for minutes, I would be surprised -- unless someone has some insider info (which I do not exclude)...
Personally, I am waiting for Collins en banc review...