Even as four firms, including State Bank of India, managed to add to their market capitalization amid high volatility on the bourses, the elite club of country's top 10 companies saw their valuations tumbling by a whopping Rs 30,000 crore in just one week.

The 10 firms, comprising six from public sector and four private sector entities, together lost Rs 30,474 crore in market capitalisation for the week ending November 21.

At the end of Friday's trade, the total market value of the 10 most-valued firms stood at Rs 9,50,253 crore, down from Rs 9,80,727 crore a week ago.

Among the losers, state-run mining giant NMDC declined the most, shedding Rs 11,874 crore in valuation, followed by another public sector company MMTC, which saw a fall of Rs 8,605 crore in market capitalisation.

Telecom giant Bharti Airtel witnessed substantial decline in its valuation, dropping Rs 5,890 crore.

Mukesh Ambani-led Reliance Industries' market value dropped by Rs 3,336 crore, accounting for nearly 10 per cent of the total losses incurred by the 10 companies.

On the other hand, apart from State Bank of India, two other public sector entities -- NTPC and BHEL -- and private sector player ITC added to their market valuation.

While SBI added Rs 828.52 crore to its market capitalisation, NTPC gained Rs 824 crore. Further, ITC and BHEL saw their valuation rising by Rs 170 crore and Rs 56 crore, respectively.

Weak global cues and heavy selling pressure battered the benchmark Sensex this week, with the 30-share index losing 470 points. However, Sensex snapped its losing streak on Friday and closed at 8,915.21 points.