Indian stocks listed on American bourses have witnessed a fall of $ 20 billion in their valuation in just one week, with ICICI Bank [Get Quote] and HDFC Bank [Get Quote] together incurring over USD eight billion loss.

Moreover, the decline of nearly 20 billion dollars, in the market capitalisation for the shares during the week ending Oct 10, is double the losses witnessed in the same period a week ago.

The 16 Indian companies listed on Nasdaq and the New York Stock Exchange have collectively seen a value erosion of $ 19.45 billion, led by ICICI Bank which lost $ 5 billion.

Reflecting the acute credit crunch in the banking sector, leading lender HDFC Bank lost $ 3.39 billion.

As the financial turmoil gripped world economies, markets globally had one of the worst weeks ever and India's benchmark Sensex had crashed over 1,000 points in intra-day trading on October 10.

Another major loser was leading software exporter Wipro [Get Quote], which saw its market capitalisation tumble by $ 3.59 billion, while IT bellwether Infosys Technologies' value crashed by $ 3.24 billion.

Even though Infosys [Get Quote] had posted a better than expected second quarter results on October 11, the firm revised its US-dollar revenue guidance.

As per the revised guidance, the full-year revenue is expected to be $ 4.72-4.81 billion compared with the previous guidance of $ 4.97-5.05 billion.

Further, IT companies -- Satyam Computer Services [Get Quote] and Patni Computers had relatively lesser declines. While Satyam's market value fell by $ 886 million, Patni had a drop of $ 87 million.

The market capitalisation of leading copper producer Sterlite Industries plunged $ 1.33 billion, while pharma major Dr Reddy's Laboratories dropped by $ 387 million.

Further, auto major Tata Motors [Get Quote] witnessed a decline of $ 470 million in its market capitalisation.

Other Indian shares listed as ADRs are internet firms Sify Technologies and Rediff, BPO companies Genpact and ExlService Holdings, telecom entities Mahanagar Telephone Nigam [Get Quote] and Tata Communications.