Immediate Or Cancel Order (IOC)

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Immediate or Cancel (IOC) Order

Key takeaways
* An Immediate or Cancel (IOC) order attempts to execute immediately and cancels any portion that cannot be filled right away.
* IOC orders can be entered as market or limit orders. They allow partial fills.
* IOC is a time-in-force instruction used to control execution speed and exposure in fast-moving or illiquid markets.

What is an IOC order?

An Immediate or Cancel (IOC) order is a trade instruction to buy or sell a security that must execute immediately—either in full or in part—and automatically cancels any remaining unfilled portion. It is a time-in-force option traders use to limit how long an order remains active and to avoid unintended exposure.

How IOC works

  • IOC limit order: specifies a price and will execute immediately at that price (or better) for any available quantity; any unfilled remainder is canceled.
  • IOC market order: has no price limit and executes immediately at the best available prices for any quantity available; any unfilled remainder is canceled.
  • Partial fills are acceptable. Unlike Fill or Kill (FOK) or All or None (AON) orders, IOC does not require the entire quantity to be filled.

IOC versus other time-in-force orders

  • Fill or Kill (FOK): must be filled entirely immediately or canceled (no partial fills).
  • All or None (AON): must be filled in full, but not necessarily immediately (depends on other instructions).
  • Good ’Til Canceled (GTC): remains active until executed or canceled (often limited by broker policies).

When to use an IOC order

Use IOC orders when you want:
* Immediate execution without leaving unfilled orders lingering in the market.
* To limit exposure to rapid price moves or to avoid getting filled at widely varying prices.
* To manage large orders that could otherwise be executed piecemeal at unfavorable prices.
* Short-term or intraday traders who don’t want to track and cancel leftover orders manually.

Examples

  1. Market IOC example: You place an IOC market order to buy 1,000 shares. If only 500 shares are available at current offers, those 500 shares are filled immediately and the remaining 500 shares are canceled.
  2. Limit IOC example: You place an IOC limit order to buy 1,000 shares at $169. If no shares are available at $169 at the moment the order reaches the market, the order is canceled immediately and will not wait for later offers.

Benefits

  • Faster execution and reduced risk of unwanted exposure.
  • Price protection when used as a limit IOC in fast-moving or illiquid markets.
  • Flexibility through partial fills without the requirement to fill the entire order.

Practical considerations and tips

  • Check whether your broker supports IOC and whether it allows IOC for market and limit orders.
  • IOC is useful for intraday strategies and to avoid stale orders at market close.
  • For very large orders, consider working with liquidity providers or using algorithmic execution to minimize market impact.

Bottom line

An IOC order provides a fast, controlled way to seek immediate execution while canceling any unfilled portion. It’s particularly useful for traders who want immediate action without leaving partial orders active in the market. Choose market-IOC for speed and limit-IOC for price protection.