Technical Definition
Immediate-or-Cancel (IOC) Order
An order that executes immediately what it can at the specified price/limits, then cancels any unfilled portion.
By Crypto University Editorial
Fill-or-Kill (FOK)
✦ Key Insight
Why It Matters: Useful for aggressive entries without lingering partial fills; avoids "stuck" orders in fast markets. How It Works: Tries to fill as much as possible instantly; remainder is canceled (no resting in book). Common Mistakes: Using for large sizes (partial fill only); confusing with
✕ Common Misconceptions
It is often mistaken for similar sounding terms, but the technical implementation is distinct.
Detailed Explanation
Why It Matters:
Useful for aggressive entries without lingering partial fills; avoids "stuck" orders in fast markets.
How It Works:
Tries to fill as much as possible instantly; remainder is canceled (no resting in book).
Common Mistakes:
Using for large sizes (partial fill only); confusing with FOK.
FAQs
IOC vs. FOK?
IOC allows partial; FOK requires full or nothing.
Good for scalping?
Yes — quick, no commitment.
In Practice
“Buy 10 BTC at market but only 7 available — fills 7, cancels 3 instantly.”