Immediate-or-cancel (IOC) order
An immediate-or-cancel (IOC) order executes at once whatever quantity is available at its limit price or better and cancels any remainder, so it never rests in the order book. CME calls the same instruction Fill and Kill (FAK).
Senzoukria · Glossary · Updated September 2026
Definition
IOC is a time-in-force instruction rather than an order type. Attached to a limit order, it says: match now against resting orders at the limit or better, then cancel whatever is left. The order can therefore fill completely, partially or not at all, but it never waits in the queue. On CME Globex the equivalent qualifier is Fill and Kill (FAK); crypto venues such as Binance and Bybit use the IOC name. Binance's spot documentation describes it as an order that will try to fill as much as it can before it expires.
A worked example
The ask side of the book shows 4 contracts at 5,000.00 and 3 at 5,000.25, with 20 more at 5,000.50. A buy of 10 IOC with a limit of 5,000.25 takes the 4 contracts at 5,000.00 and the 3 at 5,000.25, then cancels the 3 contracts it could not fill within its limit. The trader holds 7 contracts at an average of about 5,000.11, and nothing is left working. The same order without IOC would have left a bid for 3 contracts resting at 5,000.25.
What it looks like in order flow
- The filled part is aggressive: it prints on the tape with the IOC sender as aggressor, on the ask side of the footprint for a buy.
- The canceled remainder leaves no trace in market data. It never entered the book, so no heatmap band or DOM size ever showed it.
- A series of small IOC orders at one price is one way participants test for hidden or refilling liquidity, a practice regulators call pinging.
In Senzoukria
The full order ticket on the Trading page offers IOC among its time-in-force choices, next to DAY, GTC and FOK, and the choice is transmitted with the order to the Rithmic connection. The ticket does not restrict which order type can carry IOC; a combination the broker or exchange does not accept is refused and the refusal is shown. The compact order pad, the quick ticket on the chart and the position shortcuts always send DAY orders; IOC is set in the full ticket.
Common mistakes
- Expecting an IOC to guarantee a fill. It guarantees only that nothing will rest.
- Sizing protective orders for the full intended quantity when the IOC filled only part of it.
- Confusing IOC with FOK: IOC accepts a partial fill, FOK does not.
- Reading the DOM size at your price as available: by the time the IOC arrives, part of it may have traded or been canceled.
Related
In the same section
- Marketable limit order
- Implementation shortfall
- Imbalance ratio
- Implied orders
- Imbalance
- Implied volatility
- Iceberg order
- In-sample vs out-of-sample
Sources
This page in other languages
Frequently asked questions
- What is the difference between IOC and FOK?
- Both execute immediately or not at all, and neither rests in the book. An IOC keeps whatever part it can fill and cancels the rest; a fill-or-kill order must fill its entire quantity immediately, or nothing is filled and the whole order is canceled.
- Is an IOC limit order the same as a market order?
- No. A market order takes whatever the book offers until it is filled, within any protection range the exchange applies. An IOC limit order never pays beyond its limit price and gives up the unfilled quantity instead of chasing it.