IT bellwether Tata Consultancy Services (TCS) on Thursday became the first Indian company to close the trading session with over $100 billion market valuation.It had become the first Indian IT company on Monday to cross the $100 billion mark in market capitalisation (m-cap) in intra-day trade, but had closed the session at about $98.8 billion in value.Before TCS, Reliance Industries Ltd had breached the mark in intra-day trade on October 18, 2007. But, it too had failed to sustain that level and had closed the session below that coveted number. The US dollar was quoted at Rs 39.59 at that time.The market valuation of TCS on Thursday has been calculated on the basis of exchange rate of Rs 66.77 against the dollar in the afternoon. At the close of trade TCS’ market cap was up by Rs 13,869.81 crore to Rs 6,77,724.81 crore ($101.5 billion) following surge in the stock price amid positive March quarter earnings.Shares of the company ended 2.09% higher at Rs 3,540.35 on BSE. During the day, they gained 2.65% to Rs 3,560. On NSE, the stock went up by 1.98% to close at Rs 3,539.25.In terms of equity volume, 1.51 lakh shares of the company were traded on BSE and over 60 lakh shares changed hands at NSE during the day. The nation’s largest software exporter TCS on April 19 reported a 4.4 per cent rise in March quarter net profit at Rs 6,904 crore.