The Indian equity benchmarks edged higher on thursday ahead of monthly expiry of April futures and option contracts led by gains in Hindustan Unilever, Reliance industries, Infosys, Sun Pharma, ICICI Bank, Larsen & Toubro and Asian Paints. The Sensex rose as much as 477 points and Nifty 50 index touched an intraday high of 17,189.