South Korea's won fell to its weakest level against the US dollar since March 2009 on Friday, touching 1,549.1 won per dollar at one point during intraday trading before settling at 1,539.1 won — a drop of 9.4 won from the previous session. Foreign investors sold a net 3.5 trillion won (approximately $2.3 billion) worth of local shares, extending their net-selling streak to a 20th consecutive trading session, as fading hopes for a diplomatic resolution to Middle East tensions dampened risk appetite. The benchmark KOSPI (South Korea's main stock index) plunged 5.54 percent to close at 8,160.59, with authorities having pledged measures to curb excessive volatility in currency markets.