BENGALURU, Nov 18 (Reuters) - Indian shares were set to end the holiday-shortened week nearly 2% lower on Thursday, as losses in automobile and information technology stocks weighed on markets, while digital payments company Paytm plunged in a tepid market debut. By 0525 GMT, the blue-chip NSE Nifty 50 index (.NSEI) had fallen 0.77% to 17,761.30, while the benchmark S&P BSE Sensex (.BSESN) had lost 0.65% to 59,615.45. Both the indexes have struggled this week, hurt a combination of rising inflation worries globally, valuation concerns, and an end to the domestic September-quarter earnings season. "Because of the extraordinary monetary accommodation provided by global central banks... the valuations of many businesses (have become astronomical)," said Ajay Bodke, an independent market analyst. Broader global stock markets also slipped as rising inflation worries clouded the outlook for interest rates and growth. In Mumbai trading, Paytm"s (PAYT.NS) shares tanked as much as 26.2% in their stock market debut, whose initial public offering of 183 billion rupees is India"s biggest. read more The Nifty Auto Index (.NIFTYAUTO) fell 2.12% and was on track to snap two straight sessions of gains. Tata Motors (TAMO.NS) lost 4.2% to be the top percentage loser on the Nifty 50. The Nifty IT index (.NIFTYIT) was down 1.66% and was set to break a four-day winning streak. HCL Technologies (HCLT.NS) fell 2.8%. Sapphire Foods India (SAPI.NS), a domestic franchisee of KFC and Pizza Hut operator Yum Brands (YUM.N), gained 4.1% in its market debut. Shares of oil-to-metals conglomerate Vedanta (VDAN.NS) fell 5.6%. The company on Wednesday said it had constituted a board committee to evaluate strategic measures.