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: a 100 percent margin under the long-term framework, a 50-to-100 percent band under the short-term one, a narrower price band at the higher stages, and at the top stage a move out of rolling settlement altogether. The list is not static. NSE republishes it by circular, and the pair issued on 18 September 2026 took effect on 21 September 2026.

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. NSE's ASM circular of 18 September 2026 lists the governing circulars as NSE/SURV/39265, 45111, 46557, 48506, 52090, 63362 and 64066, dated 27 October 2018, 22 July 2020, 4 December 2020, 4 June 2021, 22 April 2022, 9 August 2024 and 20 September 2024. The margin is 100 percent. Note that the margin date and the shortlisting date are not the same: in the 18 September 2026 circular the securities were shortlisted with effect from 21 September 2026, while the 100 percent margin applied from 23 September 2026 on positions open as at 22 September 2026. Securities qualifying under criterion VII, the Stage IV criterion, are additionally shifted out of rolling settlement (series EQ) into the trade-for-trade segment (series BE), which means every trade in them must be settled by delivery.

Short-term ASM runs two stages and reacts faster, and its margins are graduated rather than flat. At ST-ASM Stage I the applicable margin is 50 percent or the existing margin, whichever is higher, capped at 100 percent, applied in the same circular from 22 September 2026 on positions open as at 21 September 2026. At Stage II it is 100 percent or the existing margin, whichever is higher, on the same cap. 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. Source: NSE circulars NSE/SURV/76428 and NSE/SURV/76429, both dated 18 September 2026, read 20 September 2026.

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

How many stocks move in a typical ASM review?

Fewer than the phrase "the ASM list" suggests. A review republishes the whole framework, but the number of securities actually changing state on any one date is usually small. The 18 September 2026 circulars, effective 21 September 2026, moved these:

Source: annexures to NSE/SURV/76428 and NSE/SURV/76429 dated 18 September 2026, read 20 September 2026.

Two things follow. First, membership is mostly inherited from earlier reviews rather than set each week, so "when did this stock enter ASM" is a different question from "is it on the list today". Second, the moves run in both directions on the same date: on 21 September 2026 one security stepped up to Stage IV and another stepped down from it. When a stock leaves a framework its price band is reinstated to the band that applied before it was shortlisted, unless it is still caught by another surveillance measure, in which case that measure's band prevails.

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.