My account still had 200k shares but now at $0.10/shares. For the fun of it, I put in a sell of 200k at $0.09 and it was filled immediately. The money is in my "buying power" still as the trade has not yet settled.

My question is has anyone seen this happen before. Basically I am thinking my online broker made a mistake and did not cut my shares by 5. Can they reverse the trade? Do I owe them 160,000 shares? Did I beat my bank?? As I said the money is still in my buying power and am now on day 2 post-trade. Any advice/experience would be appreciated...