A currency dealer works in front of electronic boards showing the Korea Composite Stock Price Index (KOSPI) (C), the exchange rates between the Chinese yuan and South Korean won (L), and the exchange rate between U.S. dollar and South Korean won (R), at a dealing room of a bank in Seoul, South Korea, August 25, 2015. China stocks slumped about 4 percent on Tuesday, touching eight-month lows, as investors dumped shares after a grim "Black Monday" that battered global markets but failed to prompt fresh rescue measures from Beijing.