Hong Kong stocks extend gains at open

The Hang Seng Index added 0.32 percent, or 98.06 points, to 31,191.51.

But the benchmark Shanghai Composite Index was down 0.16 percent, or 5.04 points, at 3,109.17, and the Shenzhen Composite Index, which tracks stocks on China's second exchange, dropped 0.07 percent, or 1.30 points, to 1,776.43.