The combined market valuation of five of the top-10 most-valued firms tumbled Rs 1,85,952.31 crore last week, with HDFC Bank taking the biggest hit, in-line with a weak trend in domestic equities. Last week, the BSE benchmark slumped 1,844.2 points or 2.32%, and the Nifty dropped 573.25 points or 2.38%. The market capitalisation of HDFC Bank dropped by Rs 70,479.23 crore to Rs 12,67,440.61 crore.