How long should I hold a losing stock before selling?

Hey everyone,

I'm pretty new to investing and could really use some advice. I bought some shares in AMD about 2 months ago, and they're down about 15% now. I keep checking the price every day hoping it'll go back up, but it just seems to keep dropping.

I know the general advice is "buy and hold" and "time in the market beats timing the market," but honestly, I'm starting to get nervous about losing more money. At what point should I just cut my losses and sell? Is there a specific percentage drop that most people use as their "get out" point?