Global leveraged exchange-traded fund managers are stepping up their push into South Korea, drawn by retail investors whose appetite for high-risk US-listed products has made them a significant source of assets. Russell Tencer, president of Tradr ETFs, visited Seoul on Thursday to meet Korean investors and promote the firm’s lineup. His trip marked the second visit by a foreign manager specializing in leveraged ETFs since Korea allowed single-stock leveraged funds to begin trading in late May.