This happened to me yesterday. I was scaling out a position with three contracts on MSFT calls with a trail stop. Then I wanted to change the three contracts to two in TWS order line. I just finished changing it to 2 and transmited the change. All of sudden, the order got executed. Guess what happened? It sold five contracts.:eek: Somehow, TWS messed up the order size during the change while the order got executed. Have you encountered similar experience in TWS?