# Everything you need to know about the Closing Auction Session (CAS), starting August 3
**URL:** https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801
**Category:** General
**Created:** [July 10, 2026, 11:03am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801 "2026-07-10T11:03:37Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@nithin\_kumrr](https://tradingqna.com/u/nithin_kumrr)
#### Post date: [July 10, 2026, 11:03am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/1 "2026-07-10T11:03:37Z")
There’s a new Closing Auction Session (CAS) coming from August 3, and it’ll change how the closing price is discovered for F&O stocks. We’ve explained the changes here.
**English:**
[ ](https://www.youtube.com/watch?v=h2_ic-pCzB4)
**Hindi:**
[ ](https://www.youtube.com/watch?v=X8Ri23wtc9Q)
Give it a read:
> **[Everything you need to know about Closing Auction Session (CAS)](https://zerodha.com/z-connect/general/everything-you-need-to-know-about-closing-auction-session-cas)**
>
> Important changes from August 3, 2026: Following the introduction of the Closing Auction Session (CAS), market closing times will be as follows; there are
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### Author:  [@BB789](https://tradingqna.com/u/BB789)
#### Post date: [July 10, 2026, 12:26pm UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/2 "2026-07-10T12:26:31Z")
Looks like JS only needs to participate in CAS from now on. But is the process open enough? How would they know whether to sell/buy 100cr or 300cr to bring the price to their desired point?
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### Author:  [@pavinjoseph](https://tradingqna.com/u/pavinjoseph)
#### Post date: [July 10, 2026, 2:57pm UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/3 "2026-07-10T14:57:25Z")
JS is cooked! 🍳
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### Author:  [@Patel\_6](https://tradingqna.com/u/Patel_6)
#### Post date: [July 10, 2026, 3:13pm UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/4 "2026-07-10T15:13:49Z")
using indicative price
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### Author:  [@satheeshb](https://tradingqna.com/u/satheeshb)
#### Post date: [July 17, 2026, 5:13am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/5 "2026-07-17T05:13:28Z")
When I initiate a market order at 3:20pm, i will come to know the price at which it got executed only after the market close. Is this correct assumption? @nithin_kumrr
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### Author:  [@siva](https://tradingqna.com/u/siva)
#### Post date: [July 17, 2026, 8:10am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/6 "2026-07-17T08:10:12Z")
> [@satheeshb](#):
>
> will come to know the price at which it got executed only after the market close. Is this correct assumption?
On depth it will show probable close, as new orders enter and exit system we can’t be sure of exact close till CAS end, but it will be within 3% range of reference price derived from 3 to 3.15 trading.
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### Author:  [@captainaak](https://tradingqna.com/u/captainaak)
#### Post date: [July 20, 2026, 11:03am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/7 "2026-07-20T11:03:08Z")
But I have one doubt. Who will use the closing auction session the most? Who benefits from it? Is it institutions looking to enter and exit huge positions? Is it safe to assume that most of the liquidity might shift to the closing auction session, or am I getting it wrong somehow?
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### Author:  [@siva](https://tradingqna.com/u/siva)
#### Post date: [July 20, 2026, 11:30am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/8 "2026-07-20T11:30:10Z")
> [@captainaak](#):
>
> . Who will use the closing auction session the most?
Anyone can use, normal retail will also use but for AMC’s and all their tracking errors can reduce now and liquidity in CAS should increase is what we think.
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### Author:  [@satheeshb](https://tradingqna.com/u/satheeshb)
#### Post date: [July 25, 2026, 2:31am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/9 "2026-07-25T02:31:18Z")
After 3:20, What ever the type of order(Market or Limit), after CAS ends both type of order will have same closing price.
Correct??
@siva @nithin_kumrr
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### Author:  [@siva](https://tradingqna.com/u/siva)
#### Post date: [July 25, 2026, 2:58am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/10 "2026-07-25T02:58:52Z")
> [@satheeshb](#):
>
> after CAS ends both type of order will have same closing price.
Yes, right.
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### Author:  [@KD61](https://tradingqna.com/u/KD61)
#### Post date: [July 27, 2026, 4:02pm UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/11 "2026-07-27T16:02:52Z")
Instead of Auto-squaring off MIS stocks at 15:10 PM, isn’t it better to exit them at market order during the CAS process? More volume, so less slippage for traders due to auto square off
Like, If someone do not exit MIS stocks till 15:15: PM, Zerodha automatically place market order in CAS?
@siva
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### Author:  [@KD61](https://tradingqna.com/u/KD61)
#### Post date: [July 27, 2026, 4:06pm UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/12 "2026-07-27T16:06:58Z")
Just to make sure asking again,
Stock F&O, Index F&O will continue to trade normally till 15:40 PM? So it is possible that their price is very different from Closing Price? Since trades won’t know closing price of cash stocks?
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### Author:  [@Ragavendran\_M](https://tradingqna.com/u/Ragavendran_M)
#### Post date: [July 28, 2026, 2:32am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/13 "2026-07-28T02:32:55Z")
> [@KD61](#):
>
> Stock F&O, Index F&O will continue to trade normally till 15:40 PM? So it is possible that their price is very different from Closing Price? Since trades won’t know closing price of cash stocks?
Yes its correct.
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### Author:  [@Ragavendran\_M](https://tradingqna.com/u/Ragavendran_M)
#### Post date: [July 28, 2026, 2:35am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/14 "2026-07-28T02:35:08Z")
It’s a new closing mechanism, and we never know how it will behave during the live market. Based on this, if we keep intraday square-off at 3.30 PM, it will be riskier.
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### Author:  [@nithin\_kumrr](https://tradingqna.com/u/nithin_kumrr)
#### Post date: [July 28, 2026, 9:10am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/16 "2026-07-28T09:10:35Z")
>
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### Author:  [@sankar](https://tradingqna.com/u/sankar)
#### Post date: [July 29, 2026, 10:04am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/17 "2026-07-29T10:04:59Z")
From 3.25 to 3.30 only limit order then
Limit price higher than trading price can be placed in limit,and total sweep will happen
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### Author:  [@KD61](https://tradingqna.com/u/KD61)
#### Post date: [August 3, 2026, 3:45am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/18 "2026-08-03T03:45:29Z")
I wonder how Intraday charts will be updated after 15:15 for F&O stocks
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### Author:  [@BB789](https://tradingqna.com/u/BB789)
#### Post date: [August 3, 2026, 10:01am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/19 "2026-08-03T10:01:14Z")
> [@BB789](#):
>
> Looks like JS only needs to participate in CAS from now on. But is the process open enough? How would they know whether to sell/buy 100cr or 300cr to bring the price to their desired point?
Rofl 🤣 +200 on index? Looks like they overshot going in blindly.
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### Author:  [@bharat1080](https://tradingqna.com/u/bharat1080)
#### Post date: [August 3, 2026, 10:03am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/20 "2026-08-03T10:03:16Z")
haha… @Jason_Castelino index underlying value is higher than future.
> [@BB789](#):
>
> Rofl 🤣 +200 on index? Looks like they overshot going in blindly.
what will happen in bear market ? haha
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### Author:  [@dcd](https://tradingqna.com/u/dcd)
#### Post date: [August 3, 2026, 10:06am UTC](https://tradingqna.com/t/everything-you-need-to-know-about-the-closing-auction-session-cas-starting-august-3/195801/21 "2026-08-03T10:06:59Z")
The new system looks so wrong in Indian conditions. Earlier, as we went from 3:00 PM to 3:30 PM, every passing minute gave me more confidence about the closing price. After 3:23 or 3:26 PM even JS could not move the closing price by that much. But now, we would not be sure. Basically the trade from 3:00 to 3:15 PM has completely lost its meaning.
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