New Delhi, Jan. 7 -- It was a difficult year for the Tata Group as the conglomerate witnessed a sharp erosion in its market capitalisation (m-cap), dragged down by sharp losses in its marquee businesses.

According to data from Capitaline, 18 of the 24 listed Tata group companies declined up to 60% in a year, with crown jewel Tata Consultancy Services (TCS) emerging as the biggest drag.

IT bellwether TCS alone wiped off Rs.320,038 crore from the group market cap. Its m-cap declined to Rs.11,63,107 crore on January 5 from Rs.14,83,145 crore a year ago as the stock slumped 22% during this period, weighed down by the slowdown in discretionary spending by clients, steep tariffs by the US and a hike in H-1B visa fee.

A recent report by HSBC,...