Sensex and Nifty soared to all-time highs on September 20, fueled by robust gains across the auto, energy, and banking sectors.Today, Sensex closes at a new milestone of 84,544, up 1360 points or 1.63 per cent while Nifty after reaching a record high of 25,806 closed at 25,791 up 375 points or 1.48 per cent.Bank Nifty closes 1.42 per cent or 755 points up at 53,793, Nifty mid-cap closes 1.44 per cent or 857 points up at 60,209.All sectoral indices closed in green with auto, energy, banks, capital goods, FMCG, Power, telecom, realty and metals closed between 1 and 3 per cent up.Major sectoral indices, like Bank and Financial Services, FMCG, and Consumer Durables, achieved new highs, reflecting the rally in the frontline indices.As per the experts, the expectation of an RBI rate cut post-rate cut by Fed has fueled optimism in the market, pushing the Indian stock indices to record levels. Investors anticipate improved economic conditions and strong corporate earnings.In todays session, market sentiment seemed boosted as expectations around the FED rate cut continue to fuel optimism, with the global market showing strength. As a result, buying was seen across sectors, with consumption and realty leading the charge on Friday. Both sectors rose more than 2% in the intraday. This rally is likely driven by the possibility of interest rate cut announcements in the upcoming RBI policy, said VLA Ambala, SEBI Registered Research Analyst and Co-Founder of Stock Market Today.