BENGALURU, Oct 26 (Reuters) - Indian shares rose on Tuesday in a volatile session, led by gains in metal and auto stocks, with investors focusing on commentaries from companies over the impact of higher input costs on margins in an earnings-heavy week. The blue-chip NSE Nifty 50 index (.NSEI) ended up 0.8% at 18,268.40, while the benchmark S&P BSE Sensex (.BSESN) rose 0.63% to 61,350.26. The metals index (.NIFTYMET) rose 2.9%, lifted by higher steel prices, while the auto index (.NIFTYAUTO) gained 2%. Both the indexes rose after correcting over the past few sessions. Markets took strength from some marginal profit-booking on Tuesday and managed to close higher, with support from strong corporate earnings and global cues, said Siddhartha Khemka, head of retail research at Motilal Oswal Securities in Mumbai. Shares of Kotak Mahindra Bank (KTKM.NS) rose as much as 4% to a record high after a better-than-expected quarterly profit. "On one side companies are seeing strong recovery from the opening up, improving economy and higher commodity prices, while there are also strong negatives like higher valuations and companies are at the risk of being affected by commodity-led inflation," Khemka said. Investors will be watching out for commentary on rising input costs and their impact on margins, with many top-tier companies including India"s leading car maker Maruti Suzuki (MRTI.NS), Larsen & Toubro (LRTI.NS) and cigarette maker ITC (ITC.NS) due to report their earnings this week. Shares of housing finance company Home First Finance (HOME.NS), Orient Cement Ltd (ORCE.NS) and consumer products maker Crompton Greaves Consumer Electricals (CROP.NS) surged 4%, 6% and 3% respectively, on strong quarterly earnings. Meanwhile, analysts cautioned that a near 30% gain in India"s benchmark indexes has heated up equity valuations and warned that markets could see a steep correction in certain pockets. National Stock Exchange data on Monday showed its registered investor base surpassed 50 million unique users and saw its last 10 million investor registrations in less than seven months. Reporting by Nallur Sethuraman in Bengaluru; Editing by Shailesh Kuber Our Standards: The Thomson Reuters Trust Principles.