The benchmark indices ended lower for the second consecutive session on Monday on rising concern over the Omicron variant. At close, the Sensex was down 1,189.73 points or 2.09% at 55,822.01, and the Nifty was down 371 points or 2.18%, at 16,614.20. BPCL, Tata Steel, Tata Motors, IndusInd Bank and SBI were among the top Nifty losers.