Mumbai: Benchmark Sensex tumbled over 453 points — its biggest single session fall in one year — to close at 33,149.35 today on widespread selling triggered by widening fiscal deficit concerns. Official data showed the country’s fiscal deficit at the end of October hit 96.1 per cent of the budget estimates for 2017-18. Investors also kept their portfolios at a low ebb ahead of second quarter GDP numbers. Squaring-up of positions by participants following end of November series contracts in the derivatives segment and a weak trend at other Asian markets also weighed on sentiment, brokers said. The Sensex, after a gap down opening at 33,542.50, continued its slide to touch a low of 33,108.72. It finally settled 453.41 points or 1.35 per cent lower at 33,149.35. This was its biggest single session fall since November 15 last year, when it had lost 514.19 points. The broader NSE Nifty, after cracking below the key 10,300-mark, touched a low of 10,211.25, before finally ending 134.75 points, or 1.30 per cent, down at 10,226.55. This was its biggest single day fall since September 27 this year, when it had lost 135.75 points. (PTI)