You are right, you can simply raise your sell order. However, I once owned a start-up biopharmaceutical company which I bought at .94 cents per share, and they were bought out for $7.98 per share. Investors were informed they would need to wait for about six months before they could claim their buy-out price. I anticipated the buy-out based on my own due diligence, and the rumor was that the buy-out price would be $7.75 per share. I placed my order at this level, and when the buy-out was announced, my shares sold immediately. Others did the same as I did based on the same information. When the sale was finalized, the purchasing company stated in the financials that the sale finalized for less then the offering price. True story. Now if you are way low on your selling price, your broker might simply cancel your sell order. But why take that chance?