Swiss watch exports tumbled in August as Chinese demand remained weak and stiff US tariffs went into effect. Exports fell about 17 percent from a year earlier, the Federation of the Swiss Watch Industry said in a statement Thursday. All main markets saw double-digit declines, with China down 36 percent and the US — the watch industry’s largest market — falling 24 percent. ADVERTISEMENT“The broad-based downturn underscores the formidable headwinds the Swiss watch industry continues to face,” Vontobel analyst Jean-Philippe Bertschy said in a note. “Recent reports from several watch brands suggested pockets of resilient US demand and a tentative stabilisation in China.