In a bullish session, the Sensex surged by 676.69 points, settling at 73,663.72, while the Nifty climbed 203.30 points, reaching 22,403.85. Mahindra & Mahindra emerged as the top gainer on the Sensex, soaring by 3.93% to Rs 2,393, following its better-than-expected Q4 results.