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Market Intelligence › Basic Terminologies
What it means to be on a surveillance list, and how trading changes afterwards
Published by The Retail Trader · JUL 23, 2026 · Market Basics
Sometimes an exchange tag appears next to a stock's name and trading in it suddenly becomes difficult. This is not a punishment, nor does it say the company is a fraud — it is a surveillance mechanism.
ASM, or Additional Surveillance Measure, is applied to stocks that show unusual movement in price or volume. There is no comment here on the company's fundamentals; only the trading behaviour is watched.
GSM, or Graded Surveillance Measure, is different — it is applied to companies whose financials or fundamentals themselves look weak. It has stages, and at the higher stages trading becomes very restricted.
Depending on the stage, some of these can apply:
• Full margin has to be paid, meaning leverage is gone.
• The price band is tightened.
• Many times trading happens only in a periodic call auction, not continuously.
• In the higher GSM stages, an additional surveillance deposit is also blocked.
Checking the exchange's surveillance list before taking a position is a small habit that saves a big problem. The worst scenario is that you already hold the position and from next week the stock moves into call auction — then control over your exit slips out of your hands.
This article is for educational purposes only — it is not a buy or sell recommendation, it makes no claim of guaranteed returns, and it is not advisory. Rules, rates and mechanics are changed from time to time by the exchanges, SEBI and RBI, so verify every number yourself with your broker or an official source.