The combined market valuation of top seven Sensex companies tanked by a whopping Rs 1 lakh crore in the past week, with TCS, ONGC and RIL taking the steepest hit.

The combined wealth erosion of these top seven Sensex firms, which also include SBI, HDFC Bank, Infosys and ICICI Bank, was Rs 1,02,431.31 crore. The total market value of all these seven firms stood at Rs 20.38 lakh crore in the week before.

The Sensex concluded the week at 27,350.68, disclosing a sharp fall of 1,107.42 points of 3.89 per cent -- the worst weekly drop since December 2011.

The market capitalisation (m-cap) of ONGC plunged Rs 24,725.37 crore to Rs 2,88,277.24 crore, taking the biggest hit among top-10 firms.

TCS's valuation dropped Rs 24,043.39 crore to Rs 4,81,004.83 crore. RIL's market value plunged Rs 23,988.04 crore to Rs 2,85,834.50 crore.

The m-cap of Infosys tumbled Rs 14,993.31 crore to Rs 2,22,706.01 crore, ICICI Bank fell Rs 7,439.74 crore to Rs 2,00,670.19 crore, SBI dropped Rs 4,740.74 crore to Rs

2,32,408.20 crore and HDFC Bank dipped Rs 2,500.72 crore to Rs 2,25,270.38 crore.

On the other hand, CIL added Rs 5,621.56 crore to Rs 2,30,768.37 crore, Sun Pharma's m-cap rose by Rs 4,282.96 crore to Rs 1,74,386.96 crore and that of ITC gained Rs 3,354.44 crore to Rs 3,15,996.74 crore.

In the ranking of top-10 firms, TCS retained its numero-uno position, followed by ITC, ONGC, RIL, SBI, CIL, HDFC Bank, Infosys, ICICI Bank and Sun Pharma.