Mumbai: The combined market capitalisation (m-cap) of seven of the country's top-10 most valuable firms surged by 35,189.68 crore during the past week amid bullish stock markets. RIL, TCS, Coal India, Infosys, ITC, SBI and HDFC Bank made handsome gains, though ONGC, NTPC and Bharti Airtel saw their market value eroded. The market worth of RIL advanced from 2,26,886 crore on December 30, 2011, to 2,34,025 crore on January 7. During the week, Mukesh Ambani-led Reliance Industries lost its coveted position as the country's most valuable company to Tata Group firm TCS twice, but by the end of the week, it reclaimed the top position, pushing the IT major to second place. TCS added 1,977.08 crore to its m-cap, which stood at 2,29,259.08 crore at the close of Saturday's special trading session on the BSE. Coal India's market cap jumped to 2,01,997 crore from 1,90,027 crore on December 30, while Infosys gained 4,160 crore, taking its market value to 1,62,930 crore. In a similar fashion, ITC's m-cap rose by 1,130 crore to 1,57,035 crore. SBI also saw its market value rise by 3,191 crore to 1,06,029 crore and HDFC Bank added 5,622.6 crore to its m-cap, which stood at 1,05,449.60 crore at the end of the trading week. However, ONGC saw a 256.61 crore erosion in its m-cap, which fell to 2,19,576.39 crore at the end of the week, while NTPC lost 2,350 crore to 1,29,577 crore and Bharti's value dipped by 4,557 crore at 1,25,660 crore. The 30-share BSE benchmark Sensex gained 2.54 per cent during the past trading week.