Exchange Surveillance Department
The Exchange Surveillance Department at NSE and BSE is the real-time market monitoring function that tracks trading patterns across equity, derivatives, and currency segments for potential price manipulation, circular trading, front-running, and other market abuses, and refers suspicious cases to SEBI for investigation.
The Surveillance Department of a stock exchange is the market's first line of defence against manipulative trading practices. At NSE and BSE, the surveillance function operates continuously during market hours, running automated algorithms and pattern-detection models across millions of transactions to identify anomalies that may indicate violations of SEBI (PFUTP) Regulations and other market integrity rules.
Real-time surveillance tools deployed by exchanges include price circuit filters, volume circuit filters, trade-for-trade settlement segments for illiquid stocks, and automated flags for high-value wash trades, layering, and spoofing. The exchanges maintain sophisticated databases of market participant trading histories, enabling time-series analysis of trading behaviour around corporate announcements, results dates, and material events.
A common surveillance trigger is unusual price or volume movement in a stock ahead of a price-sensitive announcement — for example, a significant surge in call options open interest or share purchases in the days before a merger announcement. Such patterns are flagged for manual review by surveillance analysts, who examine order-level data, client-to-client trading patterns, and the relationship between the trading parties.
Exchanges have the power to impose emergency circuit breakers on individual stocks, shift stocks to trade-for-trade (T+T) settlement (which eliminates intraday netting and thereby increases the cost of manipulation), suspend trading, and require enhanced disclosures. For issues requiring deeper investigation — particularly where the trades suggest access to UPSI or organised market manipulation — the exchange refers the matter to SEBI through a formal reference or Suspicious Transaction Report (STR).
SEBI-exchange coordination on surveillance is formalised through SEBI's Secondary Market Department and the periodic review of surveillance actions. Exchanges are required to share monthly surveillance reports with SEBI covering the number of cases flagged, actions taken at the exchange level, and matters referred to SEBI. This institutional linkage ensures that exchange surveillance is not an isolated function but an integrated component of SEBI's market integrity architecture.