HONG KONG-Equities rallied in Shanghai on Monday after Chinese authorities slashed stamp duty on stock trades for the first time since 2008 as they try to support the country’s beleaguered markets. The Shanghai Composite Index surged 5.06 percent, or 154.97 points, to 3,219.04, while the Shenzhen Composite Index on China’s second exchange jumped 5.58 percent, or 105.00 points, to 1,987.67.