When you sell a put option, you agree to buy a stock at an agreed-upon price.
Put sellers lose money if the stock price falls. That's because they must buy the stock at the strike price but can only sell it at a lower price.
基本概念都在这个link里,自己学习吧。就是科普,没别的意思。
https://www.thebalance.com/what-is-a-put-option-long-short-buy-sell-example-3305880