Why are certain stocks not allowed for intraday trading?

Intraday trading is allowed only for scrips that are part of the NSE-approved F&O list. Stocks other than these are generally restricted because they may have lower liquidity, higher volatility, or are under exchange surveillance (ASM/GSM).
Scrips that are not part of the F&O list are restricted to delivery-based trading only. This means intraday buy-and-sell transactions are not allowed in these stocks, and any position taken must result in delivery.