Indian markets tumbled on Monday reacting to global risk aversion stemming from uncertainty in Europe as the Nifty index fell below the 5,000 mark for the first time since January 19 while the BSE Sensex plummeted nearly 300 points.

At 11:45 am, the 30-share benchmark BSE index was trading 1.74 percent lower at 16,538.80 while the broader 50-share NSE index was down 1.78 percent or 90.65 points at 4,996.20.

The dip mirrored a global sell-of triggered by electoral outcomes in France and Greece that increased the uncertainty in Europe over austerity policies.

New socialist French President Francois Hollande, who defeated rival Nicholas Sarkozy, has been critical of cost-cutting measures to bring down European debt while in Greece, parties that oppose stiff bailout measures have gained.

Asian stocks were also reeling under huge selling pressure with markets in Japan and Hong Kong trading under big losses.