An example. I know a guy who worked at a large HF who placed a large USO order at mkt and the offer on a complex (1000up) went bye bye before the fill. He got filled at 0.20 higher on thousands of contracts. Lost the firm six figures and was fired for his stupidity.
His problem wasn't the market order that got filled a measly 0.20 ($20.00) higher than what he anticipated. His problem was USO didn't move in his direction AND he was trading too many contracts.
