Mumbai, June 13 -- India's stock market fell 1% on Thursday, hurt by renewed geopolitical tensions between Israel and Iran, and volatility ahead of the weekly Nifty futures and options (F&O) expiry. A London-bound Air India plane crashed soon after taking off from Ahmedabad, further denting investor sentiment. The Nifty 50 closed 1.01%, or 253 points, lower at 24,888.20 on Thursday, its steepest decline since 20 May. Meanwhile, the 30-share Sensex fell 1%, or 823 points, to settle at 81,691.98. The market sell-off was broad-based, with the Nifty Smallcap index falling 1.44% and the Nifty Midcap index closing 1.6% lower. The texture of the market also appears bearish for now as Nifty saw a heavy build-up of calls. The fall in the Nifty 50 index was also accompanied by a jump of 7% in open interest of active Nifty futures contract. The Nifty has once again approached the support zone of its short-term moving average - the 20-day EMA - which currently lies around the 24,800 mark. "A decisive break below this level could lead the index back into a consolidation phase," said Ajit Mishra, senior vice-president, research, Religare Broking Ltd. A fresh flare-up in geopolitical tensions in the Middle East-media reports suggest Israel is preparing for military strikes against Iran-triggered a sell-off in other Asian markets as well. Except for South Korea's Kospi index, all Asian indices closed in the red. Among the ones that fell the most were Hong Kong's Hang Seng , down 1.31%, followed by Taiwan's Taiex that lost 0.81%, and Japan's Nikkei index that declined 0.65%. Germany's DAX index was down 1.01% and the Euro Stoxx 50 index fell 0.86%. "With returns expected to largely moderate to around 10-12% as opposed to high double digits of the past years, one needs to tread very cautiously in this market," said Nilesh Shah, managing director at Kotak AMC, adding that asset allocation was key. Alok Agarwal, head of quant and fund manager at Alchemy Capital Management, said that the Q4FY25 earnings of Nifty 500 grew by over 11%, though this average was dragged down by the Nifty 50 companies, which posted only about 3% growth. An Air India flight, with 242 passengers on board, crashed in Ahmedabad during take-off for London. The incident happened between 1pm and 2pm on Thursday....