Why are market orders blocked for deep ITM index options?
A market order is an instruction to buy the specified quantity of a scrip irrespective of the price it is available at. Since deep in-the-money (ITM) options are usually illiquid contracts, market orders are blocked.
A lack of liquidity means that the bid and ask spread in the scrip is very high and can have an immediate adverse effect on your P&L. The bid/ask price could be at a price far from the last traded price or theoretical price of the contracts. Learn how you can use a limit order like a market order in this article.