The exercise of a put option. Put to seller would usually occur when the strike price of the put is lower than the market value of the underlying security. At this point, the seller would have the option, but not the obligation to sell the asset to the option writer for a higher price than what is currently dictated by the market.
For example, consider a situation where an investor buys puts to hedge downside risk in his or her position in stock A. The investor buys three-month puts on A with a strike price of $25 and pays a premium of $1.50 . The put seller or writer who earns the premium of $1.50 assumes the risk of buying A from the investor if it falls below $25. Towards the end of the three-month period, if stock A is trading at $22, the investor will sell stock A to the put writer, and receive $25 for each share of stock A.
