Sometimes late prints will show after the close. Nothing more.
The point is not the 150, rather for us to better understand "the rules of the game". Note: TD Ameritrade is today a pure agency (after selling their stake in Knight).Quote from NY_HOOD:
what market maker will manipulate for only 150 shares? do a gtc next time and wait til 4:15. if its not executed,simply cancel. by the way,why did'nt you route to an ecn? i would ask why you use td waterhouse but i will refrain from that.