I'm no expert but I was under the impression a limit order becomes a market order once the limit price is reached. A stock I owned closed the afternoon at 0.75. I placed an after-hours limit order at .65 (probably should have been a stop limit order). There was no movement in the stock price after hours or in the morning until the stock opened at 9:45am at 0.75 the same price where it had closed the afternoon before. However, my limit order executed at 8am for 0.65 more than 10% below where it was trading. Broker claims they have the wiggle room with a limit order to get away with that. I agree it should have been a stop-limit order instead but to trade it 10% below seems unconscionable, unethical and possibly illegal. I wish I had some recourse. Thoughts on this?