For put options, yeah that's more obvious. But what about for call options? Let's say, the market is all of sudden shut down with the market price of a stock at $60, the strike on the call that you bought is at $50. Since the market is shut down so you can't sell the option anymore, do you exercise to get the stock to at least get something or do you let the option expire worthless? According to the .jpg that you posted, in the situation where the physical delivery is not possible because the stock being unavailable, it could be cash settled (I don't think OCC EVER rejects an exercise request because of unavailability of the physical assets, only in the case of the request being invalid). But at what price? At $60 market price just before the market shut down or the new price when the market is re-opened which could be much lower? What if the market price is now at $40 after the exchange is re-opened? You would've lost just because of the exercising.