The Bombay Stock Exchange benchmark Sensex lost over 86 points in the opening trade on Thursday on profit-booking. The Sensex was trading at 19869, down by over 21 points a short while ago. Similarly, the wide-based National Stock Exchange's Nifty lost over 25 points to quote at 5965.Analysts said the markets are down as investors indulged in booking profits in heavy-weight stocks after the recent Sensex gains.