At close of trade on Monday, RIL's m-cap stood at Rs 8,19,073.62 crore, which is Rs 7,226.43 crore more than that of TCS.
Reliance Industries Ltd (RIL) was the only firm among the top 10 companies to post a gain in its market valuation.
The oil-to-telecom giant saw its scrip jump 9.72 per cent to close at Rs 1,275 on the BSE.
TCS, HDFC, Infosys, Kotak Mahindra Bank and ICICI Bank were the other firms which saw a rise in their market capitalisation.
RIL and SBI were the other frontline companies that suffered a drop in their m-cap for the week ended on Friday.
The oil-to-telecom conglomerate reported a net profit of Rs 10,104 crore, or Rs 17.05 per share, in April-June.
Led by a sell-off in auto and banking stocks, the 30-share Sensex cracked 560.45 points or 1.44 pc to settle at 38,337.01.
RIL was the lone gainer among the top-10 frontline companies, adding Rs 11,415.21 crore to its m-cap.
The scrip tanked 10.73 per cent to close at Rs 1,397.75 on the BSE. During the day, it plunged 17.54 per cent to Rs 1,291.
Among the gainers, the valuation of HDFC zoomed Rs 14,941.11 crore to Rs 3,93,135.72 crore.