Billionaire banker gained on rising shares of Kotak Mahindra Bank after he sealed a $2.4 billion, all-stock deal last November for rival ING Vysya Bank, partly owned by Dutch financial services group ING. Kotak has entered the general insurance business and, in a separate venture, has teamed up with telecom magnate Sunil Mittal's Airtel M Commerce to start a payments bank to provide basic banking services.