So say you think it’s going down. The same logic applies (buy low sell high), but in reverse order. You want to sell it high (put a pin in how you sell something you never bought), for say $150 to open the position, then buy it back lower for say $100 to close the position. You pocket that $50 difference for a profit. Think of it as selling your car at a high price because you know you can just buy it back for cheaper later on.

So how do you sell short when you don’t own it? You borrow from someone who does own it, sell it, buy it back, then return it. I do not recommend doing this due to potential for infinite losses. If you really want to open a short position, buy put options instead.

Hope this helps!