The S&P BSE Sensex on Tuesday slipped below its crucial psychological level of 28,000 to settle the day 119 points lower, while the broader Nifty50 also fell below its key 8,600-mark.
The 30-share index ended the day at 27,976, down 118.82 points, while broad-based 50-share index quoted 8,590, down 45.00 points at close.
Investors hope uncertainties about the much-delayed GST bill would be cleared as state finance ministers meet FM Arun Jaitley to discuss it ahead of a debate in the Rajya Sabha.
The Bank of Japan is expected to ease policy after Governor Haruhiko Kuroda said on Saturday he would do so, if necessary, to achieve the 2 per cent inflation goal.
The US Fed is expected to keep interest rates unchanged, according to a Thomson Reuters poll, but investors closely await its statement for clues on policy direction.
"The market is reflecting a combination of cautious sentiments and profit-booking today," told Anand James, chief market analyst at Geojit BNP Paribas Financial Services to Reuters.
"After NSE and BSE recorded huge gains on Monday, investors booked profits, partly due to the uncertainties surrounding the tax bill."
Dr Reddy's stock was the worst performer on both the benchmark indices and tanked 5 per cent after the pharma major said its quarterly profit slumped 75 per cent, hurt by fierce competition in its largest market, the United States.
Shares of Lupin fell as much as 1.63 per cent after gaining around 10.9 per cent so far this month as of Monday's close.
Cement companies ACC and Ambuja Cements rose as much as 2.04 per cent and 1.86 per cent, respectively, ahead of their results scheduled later in the day.
(With inputs from Reuters)