Why are market orders blocked for long-dated options?

A market order is a directive to purchase a definite quantity of stock no matter what price it is sold at. Typically, long-dated options are illiquid contracts, so the market orders are blocked.

Due to the shortage of liquidity, the bid and ask spread in a scrip is quite high and can have an instant and severe consequence on your Profit and Loss. The bid or ask price could be placed at a price that’s far off from the last traded price or the theoretical price of the contracts.