Dropping France's AAA status and Austria a step down from AAA+ to AA+ and Italy to two notches from A+ to BBB+.
Mass downgrade has affected the market sentiment as concerns over added European financial troubles that may hinder the global growth.
At 10.05 am IST, the 30-share BSE Sensex was at 16072.13 down by 82.49 or 0.51% and NSE Nifty was trading at 4836.05 down by 29.95 points 0.62%.
In Asia, all the major markets opened in red, the Nikkei 225 was down by 130.81 points and was at 8369.07. The Hang Seng was down by 182.57 points and was at 19,021.85. The Shanghai composite was down by 12.60 points and was at 2,231.98.
Among Sectoral indices on BSE, all the sectors were trading in negative terrain except IT, TECK and FMCG which were up by 0.46%-0.89%
On the National Stock Exchange (NSE), the top volume gainers were Maruti, Bharti Airtel, Tata Power, TCS and Infy posted gains between 0.94%-1.65%
And the top losers in the opening trade were Reliance Power, JP Associates, Sesa Goa, Reliance communications and Sun Pharma were top losers.