BENGALURU, Dec. 7 -- As automation seeps further into workflows across industries, India's largest IT services companies are feeling the pressure, not just on revenue, but also in their standing among the country's corporate elite.

Simply put, four of India's largest IT services firms-Tata Consultancy Services Ltd, Infosys Ltd, HCL Technologies Ltd, and Tech Mahindra Ltd-once held a "villa" in the BSE Sensex. But as automation tools ate into their domain, they have been forced into smaller accommodations.

A Mint analysis shows that four of the country's five largest IT services companies, which once made up 19% of the benchmark index, now account for just over 11%, the lowest in 18 years. My colleague Dipali Banka and I bring you the de...