Shares of Mukesh Ambani-led Reliance Industries fell as much as 9 per cent, its biggest single-day fall since March 20, 2020, to hit an intraday low of Rs 2,365 on the BSE after government announced an export tax on petrol, diesel and jet fuel (ATF) shipped overseas by firms like Reliance Industries Ltd, and imposed a windfall tax on crude oil produced locally by companies such as ONGC and Vedanta Ltd.