I used to understand the option exercise panel in TWS.. I'd select "lapse (do not exercise)", and something would be set indicating that the options would not be exercised. But I tried it a few minutes ago with FB $29 options that expire today and were about to go in the money. TWS popped up a message saying that I could not have an order on both sides of the market. It cancelled my limit order to sell at $.80 and TWS shows a filled buy order for $0.0. My trades panel and audit trail show that my position was sold for $0.0. All this while the market was $.10x$.15, with hundreds of contracts showing at the bid and ask. Did I misunderstand what setting option exercise does?