Buying new put or call options for a stock is restricted in the last two trading days before expiration (Wednesday and Thursday) because these contracts are subject to physical settlement, which involves the actual delivery of the underlying stock. However, you can still close out existing positions on these options for the quantity you currently hold.

Note: Margin requirements can significantly increase if your options are due for physical settlement. This is because you may be required to own the underlying stock, which can be a large financial commitment. Additionally, stock options can be illiquid, making it difficult to quickly sell your position if necessary.