NEW DELHI: A sharp 7 per cent drop in the benchmark Sensex ever since Prime Minister Narendra Modi launched his demonetisation drive on November 8 made desi billionaires poorer by over $1 billion, with Tatas, Birlas and Mahindras taking the biggest hit in value terms.Data compiled by ETMarkets.com showed the promoters of Tata group firms and those of AB Birla and Mahindra group companies together have lost a whopping $9 billion in market valuations in just eight sessions.While all major domestic industrial groups witnessed losses due to a selling spree in their stocks, the Mukesh Ambani-led Reliance group remained least impacted.Promoters of 27 Tata group firms combined lost Rs 39,636 crore in wealth between November 8 and November 21. TCS, where promoter holding stood at 73.33 per cent as of September 30, saw promoters lose Rs 21,839 crore in wealth due to the steep market correction.Tata Motors (down by Rs 8,954 crore), Titan (down by Rs 3,131 crore) and Tata Steel (down by Rs 1,128 crore) were other three Tata group companies, where promoters saw wealth erosion.The Tata firms were also hit by the events that erupted after Cyrus Mistry’s ouster as Tata Sons Chairman.AV Birla group promoters took a Rs 15,819 crore hit. The maximum damage of Rs 10,678 crore in aggregate was suffered by the UltraTech promoters, who held 62.26 per cent stake in the company as of September 30, 2016.Promoters of Grasim Industries (Rs 1,520 crore) and Hindalco Industries (Rs 794 crore) also witnessed wealth erosion.Promoters of Mahindra group firms lost Rs 6,100 crore in eight sessions. Promoters of M&M and M&M Financial lost a combined Rs 5,278 crore in wealth. Tech Mahindra and Mahindra Holidays, too, were impacted, but not severely.Promoters of Mukesh Ambani-led Reliance group lost only 1.78 per cent of their wealth, or Rs 2,760.6 crore, over the past eight sessions. Reliance Industries (down by Rs 1,748 crore) and TV 18 Broadcast (Rs 704 crore) were among the worst hit firms in the group in value terms.In percentage terms, Shriram group promoters’ lost the most as their wealth fell by 21 per cent, or Rs 2.772 crore, to Rs 9,913 crore. Piramal group promoters lost 14 per cent whole Anil Ambani’s Adag group promoters also saw a similar cut.Munjal (down 13.52 per cent), OP Jindal group (down 10 per cent), Murugappa Group (down 10 per cent) and Adani (down 9.83 per cent) were among the entities where the promoters lost about one-10th of their wealth in these eight sessions.