Domestic stock markets fell more than 4 per cent on Monday after the government extended the world's biggest lockdown to curb the spread of the coronavirus (COVID-19) pandemic until May 17 with few relaxations. The S&P BSE Sensex index tumbled as much as 1,752.55 points to 31,965.07, having started the session down 969.48 points at 33,717.62. The broader NSE Nifty 50 benchmark declined to as low as 9,353.40 in the first hour of trade, after starting the day at 9,533.50 as against its previous close of 9,859.90. A selloff across sectors - led by financial, automobile and metal stocks - pulled the markets lower.