Immediate-or-Cancel (IOC) Order
The Formal Definition
A conditional limit order that requires all or any partial portion of the order to execute immediately upon reaching the market venue, automatically canceling any remaining unfilled share volume.
Order Result: Executed Quantity (Instant) > 0; Unfilled Balance → Auto-Canceled (Zero Book Rest)
Cole Barrett's Reality Check
The Unvarnished Bottom Line"IOC is the surgical scalpel of active execution. You want to take whatever liquidity exists right now at your specified price, but you refuse to let an unfilled balance sit on the order book like a sitting duck waiting to be picked off after the momentum fades."
Interactive Simulator: Test the Math
Real-World Example: Scenario Breakdown
Examining the real numbers for: Fast scalping trade to buy 1,000 shares at $25.00 limit during a rapid breakout
| Execution Metric | Immediate-or-Cancel (IOC) Order | Standard Day Limit Order |
|---|---|---|
| Fee / Rate | Pro-rated per-share fee | Fixed ticket minimum |
| Spread / Buffer | Only 400 shares available at $25.00 | Filled 400 shares; remaining 600 sat on book at $25.00 |
| Execution / Status | Filled 400 shares instantly; 600 canceled automatically | Stock reversed to $24.20; late tranche filled at top of wick |
| Total Cost / Result | Avoided being filled at stale prices when the breakout stalled | Trapped in an expanded losing position |
How Brokers Weaponize This Term
Simplified platforms disable IOC time-in-force parameters to ensure resting retail orders remain open on public order books, providing predictable liquidity for their internal market-maker partners.
Broker Evaluation Matrix
Cole Approves
Interactive Brokers / Charles Schwab (TOS): Native support for sub-millisecond IOC, FOK, and GTC routing on multi-exchange order books.
Read Audit →Cole Flags / Avoids
Simplified Retail Portals: Restricts order duration to basic Day or GTC, preventing instant-or-cancel execution.
View Trap Details →Frequently Asked Questions
How does an IOC order differ from a Fill-or-Kill (FOK) order?
An IOC order allows partial fills and cancels the remaining balance; a Fill-or-Kill order requires the entire order quantity to fill immediately, or the whole order is canceled.
Can you use IOC orders in extended-hours trading?
Yes. IOC orders are frequently used in pre-market and after-hours trading to execute against thin resting liquidity without leaving stale bids exposed.