India, Aug. 13 -- After a 40-year association with the Tata Group, Natarajan Chandrasekaran on Wednesday said he had decided to step down as chairman of Tata Sons when his current term ends, citing lack of unanimous support for his reappointment from the board of the holding company of the salt-to-software conglomerate.

Shares of the group's listed companies lost $4.5 billion in market value after the announcement. Tata Consultancy Services, slumped 3.9% and was the biggest loser on the Nifty, dragging benchmark indexes lower. Jaguar Land Rover-parent Tata Motors Passenger Vehicles closed down 1.3%, while jeweller Titan and Tata Steel slipped 0.6% and 1.1%, respectively.

The decision came days before the Tata Sons annual general meeting...