TCS, Coal India, Infosys, NTPC and Bharti Airtel made gains, while RIL, ONGC, ITC, SBI and HDFC Bank saw erosion in their m-cap.

Net, the top 10 saw erosion of Rs 17,251 crore in value during the week.

Billionaire Mukesh Ambani-led Reliance Industries on Friday lost its position as the country's most valued company to IT giant TCS, part of the salt-to-software conglomerate, the Tata group.

RIL's market value fell Rs 17,535 crore to Rs 2,26,886 crore, whereas TCS advanced Rs 969 crore to Rs 2,27,282 crore.

The share price of RIL also took a hit of over 7 per cent last week to a several year low of Rs 690 as on December 30.

State-run ONGC saw a dip of Rs 3,935 crore in its m-cap, which was at Rs 2,19,833 crore; ITC lost Rs 2,921 crore at Rs 1,55,905 crore; SBI fell Rs 1,832 crore at Rs 1,02,838 crore and HDFC Bank's value dipped Rs 2,466 crore at Rs 99,827 crore.

The combined market-cap of these five firms got eroded by Rs 28,689 crore last week.

However, Coal India Ltd (CIL) added Rs 473 crore to its m-cap, which was at Rs 1,90,027 crore; Infosys saw its value swell by Rs 4,031 crore to Rs 1,58,770 crore; NTPC's valuation surged Rs 1,237 crore to Rs 1,31,927 crore and Bharti saw a rise of Rs 4,728 crore to Rs 1,30,217 crore.

These companies added Rs 11,438 crore to their value.

The BSE 30-scrip barometer Sensex suffered a loss of 283.78 points last week.