What Is the ASM List? NSE and BSE Surveillance (2026)

The ASM list is the set of stocks that NSE and BSE have placed under the Additional Surveillance Measure, a framework SEBI and the exchanges run jointly to flag securities showing unusual market behaviour. A stock lands on the ASM list because of how it is trading, not because the exchange has reached a conclusion about the business. The practical effect is tighter trading conditions, usually a 100 percent margin requirement and, at higher stages, a narrower price band.

What puts a stock on the ASM list?

Shortlisting for the ASM list runs on objective criteria decided jointly by SEBI and the exchanges. NSE's ASM FAQ lists the market-based parameters used: high-low variation, client concentration, close-to-close price variation, market capitalisation, volume variation, delivery percentage, number of unique PANs, and PE.

Those parameters combine into entry criteria. One long-term criterion, for example, requires a high-low price variation over three months greater than 150 percent plus the stock's beta times the Nifty 50 variation, and concentration of the top 25 clients at 25 percent or more of combined NSE and BSE volume over the last 30 days, and market capitalisation above 100 crore rupees on the review date. The conditions are cumulative, which is why a stock can run hard and still stay off the list if the buying is not concentrated.

Short-term ASM and long-term ASM

The framework has two halves, and they are calibrated differently.

Long-term ASM runs four stages and applies seven entry criteria, set out in NSE circulars NSE/SURV/52090 dated 22 April 2022 and NSE/SURV/64406 dated 20 September 2024. At Stage I the applicable margin is 100 percent from the T+3 day. At Stage II the price band is cut to the next lower level and the 100 percent margin continues.

Short-term ASM runs two stages and reacts faster. One Stage I trigger is a close-to-close price variation of 25 percent or more, adjusted for the stock's beta times the Nifty 50 variation, over five trading days, together with top-25-client concentration of 30 percent or more of combined NSE and BSE volume over those same five days.

A stock in the long-term framework is not simultaneously governed by the short-term one.

How long does a stock stay on the ASM list?

Under the long-term framework, a security completing 90 calendar days becomes eligible to exit, subject to a stage-wise test, and NSE reviews stages weekly. Exit is sequential: a stock in Stage IV moves to Stage III when it stops meeting Stage IV entry criteria, and so on down to Stage I, from which it can leave the framework entirely.

Because the review is periodic rather than continuous, the list you read today reflects the most recent review, not this morning's tape. Changes are announced by circular, typically after market hours one trading day before they take effect.

What the ASM list does not tell you

This is the part most summaries get wrong. NSE's FAQ answers the question directly: shortlisting under ASM "is purely on account of market surveillance and it should not be construed as an adverse action against the concerned company / entity."

ASM is also not the same thing as the GSM framework, which is built on the company's fundamentals rather than its trading pattern. A stock can sit under both at once, and the exchanges publish a combined surveillance indicator when it does.

How to read an ASM entry alongside filings

An ASM tag tells you the exchange saw concentrated or volatile trading. It does not tell you who was trading. The disclosure record is where that question gets answered, and the two are worth reading together:

• Check the bulk and block deal tape for the same dates. A concentration-driven ASM entry sometimes lines up with disclosed large trades. See how to read a block deal disclosure.
• Check the quarterly shareholding pattern for whether promoter, FII or DII holding moved across the period. See how to read a shareholding pattern.
• Check for pledge activity, since forced sales can show up as volume. See what is pledge invocation.
• Note the stage, not just the presence. Stage I and Stage IV are very different constraints.

Flock reports the filings themselves, each stamped with its date and linked back to the exchange or regulator that published it. The surveillance list is the exchanges' own; what any of it means for you is your call to make.