Why India's new closing auction is hurting options trading and worrying brokers

Dalal Street's index-options market could face pressure in the near term after a new closing auction system triggered sharp swings in stock prices during the final minutes of trading, raising concerns for options traders, brokers and stock exchanges.The closing auction system, introduced on August 3, determines the official closing prices of stocks that have derivatives contracts. Since several of these stocks have significant weight in benchmark indices, their closing prices can influence the Nifty 50 and Sensex and, in turn, the value of index derivatives.A Reuters report, citing Bernstein, said the new system is likely to weigh on trading volumes and capital-market stocks in the near term, although the research firm expects the market to adjust to the system over the coming months.WHAT IS THE NEW CLOSING AUCTION SYSTEM?The closing auction system determines the official closing price of eligible stocks at the end of the trading session. The change is particularly important for the Indian derivatives market because stocks with futures and options contracts can have a significant impact on the final levels of the Nifty 50 and Sensex.That means the closing price of individual stocks can influence index levels used to settle derivatives contracts. India is also one of the world's largest equity-derivatives markets, making any significant change in trading activity important for brokers, exchanges and traders.WHY ARE THE FINAL 15 MINUTES IMPORTANT?The biggest change so far has been seen in trading activity towards the end of the market session.Bernstein's analysis showed that trading during the final 15 minutes has fallen sharply. It now accounts for around 1.6% to 2.3% of daily turnover on the NSE, compared with a historical average of 10.1%.The decline in participation has resulted in thinner liquidity during the closing window.With fewer trades taking place, stock prices can move sharply even with relatively small orders. This makes it harder for traders to estimate where a stock or index is likely to finally close.WHAT DOES THIS MEAN FOR OPTIONS TRADERS?The change can have a direct impact on people trading index options.Bernstein said retail traders selling options are seeing an erosion in the value of their positions, while buyers can see sharp gains or losses when indices move significantly during the closing auction.For an options trader, the final price of an index is particularly important because even a relatively sharp move close to the end of the session can change the value of an option position.This means the new closing mechanism could make the final part of the trading day more difficult to navigate, particularly when liquidity is thin.WHY BROKERS COULD ALSO BE AFFECTEDThe impact is not limited to traders.Lower index-options volumes could put pressure on retail-focused discount brokers, which depend on trading activity and orders for revenue.Stock exchanges could also be affected because they earn fees based on options premium turnover.This makes the closing auction an issue for the wider capital-markets ecosystem, rather than just derivatives traders.BERNSTEIN EXPECTS THE SYSTEM TO SETTLEDespite the disruption, Bernstein does not expect the current situation to continue indefinitely.The research firm expects the new closing auction system to settle over the coming months as market participants adjust to the new process.However, Bernstein expects the transition to weigh on trading volumes and capital-market stocks in the near term.Reuters reported that Bernstein analysts Manas Agrawal and Himank Sangai said the closing auction had become a major topic of discussion among investors, particularly because of concerns about its impact on market volumes.WHY ARE THERE CONCERNS ABOUT UNUSUAL PRICE MOVES?The sharp swings during the closing auction have also raised concerns about unexplained price movements.Bernstein pointed to instances where prices moved sharply within the auction window even though the gap between the pre-auction price and the final closing price was relatively modest.This has led to concerns about possible order "spoofing" during the thinly traded closing period.Passive funds have largely avoided participating in the closing window so far. However, they may need to participate on days when benchmark indices are rebalanced.For investors who mainly hold stocks for the long term, the immediate impact may be limited.The bigger impact is on index-options traders and participants whose positions depend on the final Nifty 50 or Sensex levels.The key issue is whether the decline in liquidity during the closing minutes remains temporary or results in a sustained reduction in index-options trading volumes.For now, Bernstein expects the market to adjust to the new closing auction system. But until liquidity improves, traders may need to contend with sharper price movements and greater uncertainty around the final minutes of the trading session.(Disclaimer: The views, opinions, recommendations, and suggestions expressed by experts/brokerages in this article are their own and do not reflect the views of the India Today Group. It is advisable to consult a qualified broker or financial advisor before making any actual investment or trading choices.)- EndsPublished On: Aug 11, 2026 15:34 IST