SEBI mandates introduction of a Closing Auction Session (CAS) in the equity cash segment, from 3rd August 2026, initially applicable to securities with listed derivatives and preserving VWAP-based closing for others. CAS is prescribed as a 20-minute separate session (3:15-3:35 pm) with specified sub-periods, random order-entry close, allowable order types (limit and market), equilibrium-price matching rules, +/-3% price band from a VWAP/LTP-based reference price, carry-forward of CTS limit orders (subject to modification rules), order-level margining, dissemination requirements and existing cash-market risk controls. The Pre-Open Auction Session framework is aligned with CAS mechanics (timings, order priority, dissemination). Stock Exchanges and Clearing Corporations must jointly formulate SOPs within 30 days.