The benchmark Sensex and Nifty are likely to open marginally lower on January 3 as trends in the GIFT Nifty indicate a negative start for the broader index with a loss of 70.5 points. On January 2, the BSE Sensex was down 380 points at 71,893, while the Nifty50 fell 76 points to 21,666 and formed a bearish candlestick pattern with a long lower shadow on the daily charts indicating some buying.