Markets ended almost unchanged in a volatile trading session on Tuesday, taking a breather after a strong surge in the last few days following Union budget. Initially, supportive global cues led to a firm start however profit-taking in the latter half trimmed all the gains. The BSE Sensex ended at 51,329.08, down 19.69 points. The Nifty closed at 15,109.30, down 6.50 points.