If your employer has a stock purchase plan you can usually buy the stock at a 15% discount and then, in most cases, sell it immediately for a guaranteed 15%, or more gain. That's a no brainer.
I seem to remember the one I participated in required you to hold the stock for a specific amount of time. Otherwise, you sold at the lesser of the present value of the stock or the price you paid when you bought it. I want to say Cumulus had the same requirement, though I’m having to remember back about 20 years and could be wrong.