The South Korean won-dollar exchange rate broke below 1,390 for the first time in 11 months on August 21, closing at 1,392.6 won after dipping as low as 1,384.1. SK Hynix's announcement to buy back and cancel its entire 40 trillion won share repurchase program and return more than 50% of free cash flow from 2025 to 2027 drove the KOSPI higher by 381 points, or 5.89%. Foreign investors returned with net purchases of 1.71 trillion won that day, extending their buying streak. The development follows the U.S. Treasury's decision to double long-term Treasury buyback sizes, contributing to a dollar index near 98. Corporate dollar conversions and a record trade surplus are supporting the won, though analysts note potential impacts on exporters and the National Pension Service's hedging strategy. SK Hynix's move is seen as the most aggressive among global peers, with expectations that Samsung Electronics will follow suit.