What Is IOC (Immediate-Or-Cancel) Order?
An Immediate-Or-Cancel order tries to execute right away. Whatever portion can be filled at the limit price (or market) is filled; whatever can't is cancelled instantly. There's no resting time on the order book.
IOC orders are used to enter or exit fast without leaving residual quantity sitting visible on the book. Common in algorithmic execution where signaling matters: an IOC won't reveal intentions by sitting around if not fully filled.
Retail traders rarely use IOC explicitly because broker UIs don't always expose it. The closest retail equivalent is a marketable limit order with explicit instructions not to rest. IOC is most relevant on professional platforms and direct-market-access (DMA) brokers.
Related terms
- FOK (Fill-Or-Kill) Order — Order that must fill the full quantity immediately or be entirely cancelled.
- GTC (Good-Till-Cancelled) Order — Order that stays active until executed or manually cancelled, typically up to 60-180 days.
- Limit Order — An order to buy or sell at a specified price or better — guarantees price, not execution.
- Market Order — An order to buy or sell immediately at the best available price — guarantees execution, not price.