When you sell a put option, a few outcomes are possible. If the price of the underlying stock remains above the strike price until expiration, the option will expire worthless, and you keep the premium received at the outset. However, if the stock price falls below the strike price, you will be obliged to buy the stock at the strike price, which could result in a loss. This loss can be offset somewhat by the premium you received when selling the option. It's important to note that the risk in put writing is substantial as you're liable to purchase the shares even if their price dramatically drops.