Last week, four of the country's top-10 most valuable companies together added Rs 81,151.31 crore to their market value, with ICICI Bank and HDFC Bank being the biggest gainers. However, the BSE benchmark index fell 156.61 points or 0.19%. HDFC Bank, Bharti Airtel, ICICI Bank and State Bank of India (SBI) have hit the market (…)