Validity tells the exchange how long your order should stay alive if it doesn't fill immediately. A Day order waits in the order book until the market closes; an Immediate or Cancel (IOC) order must fill the moment it arrives. Whatever cannot fill right away is cancelled instantly.
What is a Day order?
Day is the default validity on most order windows. Place a Day limit order at 10 am and it sits in the queue, patiently, all session. It can fill at any time, fully, partially, or not at all.
Say Kavita wants to buy 100 shares of Bharat Paints Ltd (a fictional company) at ₹520 while it trades at ₹526. Her Day order waits. If the price dips to ₹520 at 2 pm, she fills. If it never dips, the order simply expires when the market closes at 3:30 pm. The exchange cancels all unfilled Day orders at the end of the session, and nothing carries to tomorrow.
If part of her order fills (say 40 shares), the remaining 60 stay live until the close, then lapse the same way.
What is an IOC order?
Immediate or Cancel (IOC) is the impatient cousin. The matching engine tries to fill it the instant it arrives, against whatever quantity is available at your price or better. Anything left over is cancelled immediately, nothing waits in the book.
Farhan places an IOC buy for 1,000 shares at ₹250 when only 600 shares are on offer at that price. He gets 600 filled; the other 400 are cancelled on the spot. He knows his outcome within a second, instead of watching a pending order all day.
| Day | IOC | |
|---|---|---|
| If not filled instantly | Waits in the order book | Unfilled part cancelled at once |
| Partial fills | Rest keeps waiting | Rest cancelled |
| Expires | At market close | Immediately |
IOC works with both limit and market orders; the validity only controls the waiting, not the pricing.
When would I use each?
- Day suits most everyday situations: you have a target price and are happy to let the order work through the session.
- IOC suits "all-or-mostly-now" situations: you want whatever is available at your price this instant and no lingering order hanging in the book. Common in fast-moving F&O trades or when firing several orders where a stale pending order would get in the way.
What if I want an order to last beyond today?
Plain exchange validity ends at the closing bell. If you want an instruction that waits days, weeks, or months for your price, use a GTT (Good Till Triggered) order instead. See what are GTT orders at Rupeezy? A GTT sits with your broker and fires an order at the exchange only when your trigger price is touched.
Things to keep in mind
- Every unfilled Day order dies at the close. If you still want it, you must place it again the next session (or use GTT).
- With IOC, a partial fill is a real possibility. Check your trade book rather than assuming the full quantity went through.
- An IOC market order in a thin stock can sweep through several price levels before cancelling the rest; check the depth first.
- Validity and product type are separate choices: Day/IOC decides how long the order lives, while Intraday/Delivery decides what kind of position you take.
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