Cyrus Pallonji Mistry, who was replaced as the Chairman of Tata Group yesterday, was the group's sixth Chairman and only the second to not bear the Tata surname. The Shapoorji Pallonji group owned by the Mistry family is Tata's biggest single shareholder with an 18% stake. Under Cyrus Mistry's four-year tenure, the market valuation of the Tata Group almost doubled.