ASM (Additional Surveillance Measure) and GSM (Graded Surveillance Measure) are exchange mechanisms that flag stocks showing unusual price or volume behaviour — sharp price moves relative to fundamentals, concentrated ownership, or low trading activity, among other triggers.
Landing on either list typically brings tighter price bands, higher margin requirements, and sometimes trade-for-trade settlement (no intraday trading, delivery only). None of this means the company has done anything wrong — the surveillance is on price and trading behaviour, not necessarily on company conduct.
What to actually check
- Which stage/category the stock is in — the frameworks have multiple stages with increasingly strict measures.
- Whether it's newly added or has been on the list for a while and is being reviewed for exit.
- Whether the move that triggered it was accompanied by any real news, or looks purely speculative.
- How the added margin requirement changes your actual position sizing if you still want to hold it.
This information is published on the exchange websites and is free to check before you buy — a two-minute lookup that a surprising number of traders skip entirely.
Educational commentary only — not investment advice or a recommendation to buy or sell any security. See our disclaimer.