Fill or Kill (FOK) Order

A Fill or Kill (FOK) order is an instruction to execute a trade immediately and in its entirety at the specified price — or cancel it completely if the full quantity cannot be filled at once. There is no partial execution; the order is either completely filled in a single transaction or immediately cancelled. FOK orders are used by institutional investors placing large orders who cannot afford partial fills that might move the market against the remaining unfilled quantity. In India's equity derivatives markets, FOK orders are used by algorithmic traders and large proprietary desks who need certainty of complete execution at a precise price level, particularly when executing multi-leg strategies where partial fills would create unintended residual risk.