The Sensex at the Bombay Stock Exchange opened 60 points, or 0.3 per cent lower, at 17,917 Thursday morning, as investors sold stocks, amid weak Asian markets. After recovering somewhat, the Sensex stood 17 points, or 0.1 percent in the red, at 17,960, a short while ago. Other Asian markets in Japan, Hong Kong, South Korea, Indonesia, and Taiwan were modestly lower on Thursday, after US central bank chairman Ben Bernanke said the US economic outlook remains unusually uncertain.