SEBI introduced Periodic Call Auctions (PCA) in 2013 to control volatility in illiquid stocks. Stocks that meet specific illiquidity criteria, such as an average daily number of trades less than 50 and a daily trading volume below 10,000, are included. PCA involves six one-hour auction sessions throughout the trading day, starting at 9:30 AM. During the 45-minute window, participants can place, modify, or cancel orders. This is followed by an eight-minute matching period, and a seven-minute buffer precedes the next auction session. This process ensures fair price discovery and reduces excessive volatility.

Session Schedule:

Q: How does trading in illiquid stocks under PCA work, and when should one place orders?

A: To trade illiquid stocks under PCA, orders must be placed in the first 45 minutes of any six session. Orders matching within the next 8 minutes result in confirmed trades. Unexecuted orders are retried in subsequent sessions throughout the day. 

Q: Are Immediate or Cancel (IOC) and Good Till Triggered (GTT) orders allowed for stocks under PCA?

A: No, IOC and GTT orders are not allowed for stocks under the Periodic Call Auction category.

Important Note:

If an order is placed but not executed during a session, it will be retried for execution in the following sessions throughout the day. To learn more, refer to BSE FAQ (BSE) and NSE circular. (NSE)