The Sensex at the Bombay Stock Exchange gained 66 points, or 0.3 per cent, to 19,713, in early trade, today, ahead of the RBI's monetary policy review. After the Reserve Bank's policy announcement, the Sensex witnessed volatility, and after surrendering all its initial gains, stood 63 points, or 0.3 percent in the red, at 19,585, a short while ago. Stock markets in Japan, China, Singapore, Hong Kong and South Korea were trading mixed, amid concerns about Europe's sovereign debt problems