Trimming its initial gains, the Sensex at the Bombay Stock Exchange was trading just 37 points in the positive territory at 17,090 in afternoon trade, when reports last came in. After losing almost 309 points yesterday, the 30-share index rebounded by 178 points or 1.01 per cent in opening trade today to 17,230.In a similar fashion, the wide-based National Stock Exchange index Nifty was trading up by 8 points at 5,192.