BSE shares jumped 5% on September 4, 2026, after SEBI confirmed a review of its derivative settlement methodology. The regulator stepped in after the Closing Auction Session, launched on August 3, led to unexpected volatility and price fluctuations during derivative expiry days. Investors will now watch for a consultation paper from SEBI due within a week, which aims to address these concerns and stabilize the market.
Shares of the Bombay Stock Exchange (BSE) climbed 5% on September 4, 2026, following news that the Securities and Exchange Board of India (SEBI) is set to review the methodology used for derivative settlement. This regulatory action comes in response to feedback regarding the Closing Auction Session (CAS), a new system introduced by the regulator on August 3 to standardize how equity closing prices are determined.
The introduction of the CAS was intended to streamline market operations, but it has faced criticism from traders and investors due to unexpected side effects. Recent trading sessions, particularly those involving the expiry of benchmark derivative contracts, have seen unusual price swings and significant discrepancies in index levels across exchanges. In some instances, these technical vulnerabilities led to sharp, brief drops in the Sensex, which in turn caused the premiums of put options to rise by as much as 500% during the closing window.
Market participants have raised concerns about the lack of liquidity within the brief auction window. Under the current rules, the auction process accounts for a very small portion of total cash-market turnover, which is significantly lower than the volumes seen under the previous volume-weighted average price system. This lack of depth has made the system susceptible to price fluctuations, leading to worries about potential manipulation on expiry days.
BSE Managing Director and CEO Sundararaman Ramamurthy stated that the exchange is actively collecting feedback from dealers and market stakeholders to present to the regulator. The primary goal is to address these technical issues, with discussions focusing on potential adjustments to the auction process and the possibility of delinking derivative expiry days from the current CAS framework.
SEBI intends to address these concerns by releasing a comprehensive discussion paper within the next seven days. This paper will outline specific proposed amendments to the settlement framework. For investors, the next important development will be the publication of this document, as it will provide clarity on how the regulator plans to restore stability to the derivative market and whether these changes will impact the current trading structure.