Hong Kong stocks were flat at the open of business Wednesday morning ahead of the long-awaited signing of the China-US trade deal later in the day. The Hang Seng Index inched down 7.28 points to 28,877.86. The benchmark Shanghai Composite Index eased 0.12 percent, or 3.65 points, to 3,103.17 and the Shenzhen Composite Index, which tracks stocks on China's second exchange, gave up 0.10 percent, or 1.80 points, to 1,816.33. dan/hg