Wiping out all its early gains, the Sensex at the Bombay Stock Exchange dropped 122 points, or 0.6 per cent, to 19,423, amid volatile trade, a short while ago. But in the morning, the Sensex had opened with a gain of 88 points, or 0.5 per cent, at 19,634, on selective buying in fundamentally strong stocks. Stock markets in Japan, China, Hong Kong, Singapore and South Korea were trading mixed, today. The US Dow Jones Industrial Average had ended 0.9 per cent higher in Tuesday's session.