If I buy a stock at 20, and put in a stop at 18 with a limit of 17 1/2, and the stock opens at 12 , I would probably rather not sell it, thinking the pendulum always swings too far in the other direction at the open I’d rather have a chance to adjust my limit to say 15 or 16.
That’s what I mean by protecting myself with a limit
OK I’m guessing what you mean is it’s not gonna protect me because if it opens at 12 I should be out of it at 12
A stop loss will not protect you from gap downs. Still, you must use it. A stock that drops from $20 to $12 must be sold, no matter how painful the loss. That stock could continue falling all the way to $1 or even zero. Stop losses are there to save your capital, not totally, prevent you from losing monies. When you have a profit then, it protects part of your profits.

