The markets opened strong on the back of global cues and pick-up in the pace of vaccination. Tuesday's trade saw hectic activity in stocks pertaining to the 'unlock' theme, said S Ranganathan, head of research at LKP Securities. Nearing Mount 53K, however, the Sensex witnessed profit-taking across the board in afternoon trade, he observed. Vinod Nair, head of research at Geojit Financial Services, said, "During early hours, Indian markets traded strongly, following Monday's rebound in western markets, which focused on economic recovery, partially offsetting concerns over a possible change in US Federal Reserve policy in the future."