The volatile Sensex at the Bombay Stock Exchange, surrendered initial gains and moved down by 5 points in the afternoon deals. The 30-share index, which had gained 29 points in its previous trade, was trading 5 points in red at 18,757 when reports last came in.Similarly, the wide-based National Stock Exchange Nifty Index was trading 2 points in a negative territory at 5,705, a short while ago.