Stocks and US equity futures fell Tuesday amid escalating US-China tension over Taiwan and deepening worries about a global economic slowdown, risks that supported demand for havens like Treasuries. An Asian share index slid the most in three weeks, with some of the steepest falls in Hong Kong, China and Taiwan. US and European futures were also in the red as July’s equity market rebound stumbled into August. US House Speaker Nancy Pelosi is set to land in Taiwan on Tuesday and would be the highest-ranking American politician to visit in 25 years.