The combined market value of the country''s seven most valued firms diminished by Rs 28,357 crore last week, with top lender SBI and telecom major Bharti Airtel emerging as the biggest losers.

The market capitalisation (m-cap) of State Bank of India dipped Rs 10,112 crore to Rs 1,11,242 crore. Global ratings agency Moody's had downgraded the state-owned lender's financial strength on October 4.

Moody's downgraded the rating of SBI's financial strength by one notch to 'D+', citing low tier-I capital ratio and deteriorating asset quality.

It also said that there could be a likely rise in the bank's non-performing assets in the near future. The downgrade will make overseas borrowings costlier for SBI.

Its stock plunged over 8 per cent to end the week at Rs 1,751.85 on the BSE.

Bharti Airtel, too, saw its market cap drop Rs 8,848 crore to Rs 1,34,736 crore.

Besides, the market worth of Reliance Industries Ltd fell Rs 2,243 crore to Rs 2,62,413 crore, and that of state-owned ONGC's plunged by Rs 1,070 crore to Rs 2,26,249 crore.

Private lender HDFC Bank saw its market value fall by Rs 4,016 crore to Rs 1,05,050 crore.

M-cap of Infosys and NTPC dipped by Rs 1,532 crore and Rs 536 crore respectively. The m-cap of Infosys stood at Rs 1,43,955 crore, while that of NTPC was at Rs 1,37,369 crore.

In contrast to these companies, state-owned Coal India, software major TCS and FMCG giant ITC saw gains in their respective m-cap.

The market cap of TCS rose by Rs 2,192 crore to Rs 2,05,253 crore and Coal India added Rs 2,842 crore to its valuation which was at Rs 2,13,019 crore.

ITC also saw its market cap swelling by Rs 1,236 crore to Rs 1,54,838 crore.

The BSE benchmark 30-share Sensex lost 221.22 points to end the week at 16,232.54.