BENGALURU, Dec 15 (Reuters) - Indian shares inched lower on Wednesday as investors turned their focus to the U.S. Federal Reserve for signs on the pace of tapering, while recent debutant Paytm plunged after a lock-in period for institutional investors expired. The NSE Nifty 50 index (.NSEI) was down 0.18% at 17,293.9 by 0350 GMT, while the benchmark S&P BSE Sensex (.BSESN) slipped 0.17% to 58,017.74. Both indexes were set for a fourth straight session of losses. Investors were looking for clues on when the Fed will stop buying assets and start raising interest rates, while a rapid spread of the Omicron coronavirus variant also weighed on sentiment. One97 Communications (PAYT.NS), parent of digital payments firm Paytm, dropped 13% to its lowest since Nov. 22, following a dismal market debut on Nov. 18.