Benchmark indices closed firmly in the green on Tuesday, the monthly derivatives expiry day, in a session that opened under pressure from fresh US sanctions on Iran but reversed sharply in the final hour as crude oil prices fell and a newly introduced auction window delivered an unexpected late jolt to closing prices.The Nifty 50 ended at 24,334, up 115.50 points or 0.48 per cent, while the BSE Sensex gained 286 points or 0.37 per cent to settle at 77,656. The session marked the first monthly expiry under SEBI’s new Closing Auction Session regime, introduced on August 3, under which F&O stocks stop continuous trading at 3.15 pm and a 15-minute auction window determines the final closing price. Tuesday’s auction alone pushed the Nifty up 75 points and the Sensex up 126 points from their respective 3.15 pm levels, a structural quirk that caught many participants off guard.“Nifty staged over 200 points intraday reversal to close at highest level since 14 August,” noted Nandish Shah, Deputy Vice President at HDFC Securities, adding that the Closing Auction Session “surged nearly 75 points, which provided the fillip for the overall gains.”The morning session opened in the red after Washington announced sweeping new sanctions targeting Iran and its trading partners in an effort to isolate Tehran and push for the reopening of the Strait of Hormuz. Markets, however, quickly recalibrated after the measures proved less severe than feared. Brent crude fell over 3 per cent to around $89 a barrel, its lowest in a week, and WTI dropped to near $82, easing India’s import-cost concerns. The rupee responded in kind, gaining 32-34 paise to close at 95.41 against the dollar, leading Asian currency gains for the session, supported also by heavy RBI intervention. The Dollar Index slipped below the 99 mark.On the sectoral front, Healthcare, Consumer Durables, and Pharmaceuticals were the top performers. IT, Infrastructure, Media, and PSU Banks also closed in the green. Energy, Metals, and Private Banks were the session’s laggards. Among individual Nifty constituents, Adani Enterprises, Max Healthcare, and Apollo Hospitals led gains, while HDFC Life, Cipla, and ONGC underperformed. Despite the positive headline close, NSE cash-market turnover fell 4 per cent versus the previous session, pointing to subdued broader participation. Market breadth was narrow, with an advance-decline ratio of 0.94, and the Nifty Smallcap 100 slipped 0.10 per cent, even as the Nifty Midcap 100 gained 0.54 per cent to touch a fresh all-time high. India VIX declined nearly 4.25 per cent. Gold on COMEX eased 0.30 per cent to $4,637 per ounce, with domestic prices dipping around ₹300 to ₹1,62,950, as crude’s retreat and rupee strength capped safe-haven demand despite gold’s broader uptrend.Looking ahead, markets face a packed global calendar. Nvidia’s quarterly earnings on Wednesday are being closely watched as a bellwether for the global AI investment cycle and their knock-on effect on Indian IT stocks. US consumer confidence data, Fed meeting minutes, and further developments on US-Iran tensions and crude oil prices will also shape sentiment. Technically, analysts are watching whether Nifty can sustain above the 24,300–24,400 resistance band, with 24,100 as immediate support. A clean break above 24,500 would signal extension toward 24,600, while failure there keeps the index range-bound.Published on August 25, 2026