The BSE Sensex lost some of its initial gains of morning trade but was still up by 42 points during the noon trade on sustained buying by funds and retailers amid a firm trend in Asian regions. The 30-share barometer which had gained 65 points in early trade, was trading at 18,756, a shortwhile ago.Similarly, the wide-based National Stock Exchange's Nifty was up by nearly 10 points, to 5,697.