Aditya Birla Group chairman Kumar Mangalam Birla has increased his personal stake in Vodafone Idea through open market purchases in four tranches between January end and first week of February . Birla purchased 22.1 million shares on January 30, 18.8 million shares on February 1, t4.5 million shares on February 2, and 14.2 million shares on February 3 taking his cumulative acquisition to 59.6 million shares for a total outlay of Rs 66.18 crore across tranches.