Many sources only mention that if the option expires worthless, I will lose the premium as the maximum loss. But in reality, I can also lose money higher than the max loss even if my put option is in the money if I forgot to sell it before it expires? Consider the following case:
For example the stock was at $110 when I bought a strike price 100 put option at a cost of $4. That means I already paid $400 for the premium.
Let's say someone invited me to a party on the last Friday of the month, and the stock price dropped to $99 as it expires. Since it is in the money, my broker will automatically exercises it for me when it expires.
Since I don't own any stock, I have to buy 100 shares of stocks. Also my put option is exercised after the market closed, I might not be able to buy it at $99. If on Monday, the stock price rises to $110, does that mean I need to buy it at $110, and sell it to the put seller at $100?
In summary, I lose $1000 selling the stock at $100, and paid $400 for the premium, so I am at a loss of $1400. And since I am using margin to buy and sell stocks, I guess the broker will also charge me fees for that.
Therefore, as a put option buyer, my loss can exceed the theoretical maximum loss if I am careless?