SmartAPI Group

@diljeets-0

Team

What is your TAT to reply to queries.

What is CAS?

SEBI has introduced a new 20-minute auction window at the end of the trading day to determine the closing price for stocks that have F&O contracts. This replaces the earlier method of using the last 30 minutes of continuous trading to arrive at the closing price. CAS goes live from 03 Aug 2026.

What are the changes in schedule and timing?

The updated market timings are as follows:

3.15-3.20 pm: Reference price is calculated. Order entry via SmartAPI will be rejected in this phase.

3.20-3.25 pm: Limit and Market orders can be placed, modified, or cancelled.

3.25-3.30 pm: No changes or cancellations on Market Orders. Limit orders can still be placed/modified. Random close anytime between 3:28 pm and 3:30 pm.

3.30-3.35 pm: Orders are matched against each other, and the closing price is set.

3.35-3.50 pm: Transition from CAS to Post-closing session

3.50-4.00 pm: Trades settle at the Equilibrium Price discovered in the auction.

What order type restrictions will be in place?

Stop-loss and Iceberg orders for CAS-eligible stocks are disallowed between 3:15-3:40 pm.

After 3:25 pm, Market orders can no longer be modified or cancelled – only added or changed as Limit orders.

F&O trading in NFO and BFO will be extended till 3:40 pm on all trading days.

Changes to post-closing session apply to all stocks, regardless of whether they are CAS-eligible or not.

Changes in Auto-Square Off Timings

For intraday trades, the auto-square off timings will see the following changes from 03 Aug 2026.

Equity Robo Orders: 3:05 pm

Equity MIS Orders: 3:10 pm

Equity F&O Orders: 3:20 pm

How to check if a stock is CAS-eligible?

A new field, is_cas_enabled, is now available in the instrument master response. Check out the sample:

{ "token" : "99926000", "symbol" : "Nifty 50", "name" : "NIFTY", ... "is_cas_enabled" : true }

A new field, referenceLimitPrice in our Market Data API can be used to get the Reference Price. Here’s a sample response:

{ "status": true, ... "high": "191.25", "low": "185", "close": "187.80", "referenceLimitPrice": "191", }

What are “Reference Price” and “Equilibrium Price”?

The Reference Price is fixed at the start of CAS – it's the VWAP of trades between 3:00-3:15 pm (or LTP/previous close if no trades), and it sets the ±3% band within which CAS orders can be placed.

The Equilibrium Price is discovered at the end of CAS – it's the price at which the maximum quantity of orders placed during the auction get matched, using volume maximisation.

In short: Reference Price is the starting boundary for the auction, Equilibrium Price is its outcome. The Equilibrium Price becomes the stock's closing price for the day; if none is discovered, the Reference Price is used instead.

Where to get more detailed information?

You can view our full API documentation here: https://smartapi.angelone.in/docs/CASDoc

For additional reading:

“NSE To Bring Closing Auction Session: What Does It Mean for Stock Prices and Investors?” on Angel One

“SEBI Introduces Closing Auction Session to Enhance Equity Market Price Discovery” on Angel One

BSE’s official circular published on 10 Jun 2026

NSE’s official circular published on 29 May 2026

SEBI’s official circular published on 16 Jan 2026

Subject: SmartAPI connectivity — high TCP connect failure rate from registered IP

Client code: R58519218
Registered IP: 142.93.211.114

I am seeing a high rate of failed TCP connections to apiconnect.angelone.in from my registered server IP. Measured just now: 3 out of 10 fresh HTTPS connects succeeded; the rest timed out at 5 seconds. Login attempts (generateSession) are failing repeatedly as a result. An MTR trace shows ~49% packet loss at the destination hop.

My hosting provider recently resolved an unrelated upstream block on this IP, and other destinations have since recovered fully, so I am trying to determine whether anything on the SmartAPI side is contributing.

Could you please check:

Is the IP 142.93.211.114 currently registered and in good standing for my API access? Is there any rate limiting, throttling, or block applied to this IP, possibly triggered by repeated failed connection attempts over the past few days? Are there any known connectivity issues affecting apiconnect.angelone.in?

I can provide full MTR output on request.
Angel's SmartAPI docs state the session remains active till 12 midnight unless the user logs out. Confirm our angelone_papa lazy-login model and any expiry assumptions match that documented behaviour — and check we haven't invented another "~" constant the way commit 918bca1 did for Kite. If we have an assumed Angel expiry anywhere, replace it with the documented rule and cite the source in the code comment.

Team,

Some more info in addition to the above.

I trade commodities starting morning till 10.00 pm.

I get this error exclusively between 9.00am to 3.30pm when NSE/ BSE markets are open.

Post 3.30pm I stop getting this error.

Hence the theory there could be an issue with the code OR multiple requests are being send is completely ruled out.

This is definitely Server throttling issue caused due to same API endpoint getting multiple hits.

What is weird is, me getting this error despite sending the request within rate limit (sending single request at every 2sec interval).

Having Rate limit check at server makes no sense, for those users sending requests within limits are still getting this error.

Expecting a resolution soon.

Regards
Diljeet