An electronic board on the exterior of a Hana Bank branch in central Seoul shows the Korean won quoted at 1,510.9 per dollar during daytime trading on Wednesday. (Newsis) The South Korean won weakened past the 1,510 per dollar level in intraday trading Wednesday, hitting its lowest level in more than a month as soaring US Treasury yields and heavy foreign selling in local equities pressured the currency.The won opened onshore trading at 1,509 per dollar and quickly fell past the 1,510 threshold. It later weakened to as low as 1,513.4 before trading at around 1,512.5 as of 2 p.m.The currency breached the 1,510 level during daytime trading for the first time since April 6.The won had shown signs of recovery after stabilizing in recent weeks following volatility triggered by the Iran war: The average monthly won-dollar exchange rate eased to 1,485 in April from 1,492.5 in March.But the currency is under renewed pressure this month as prolonged geopolitical tensions, surging US yields and massive foreign outflows from Korean equities fuel demand for the dollar.The latest selloff was largely driven by a sharp rise in long-term US Treasury yields. Overnight, the yield on the 30-year US Treasury bond briefly approached 5.2 percent, its highest level since 2007 before the global financial crisis. The benchmark 10-year Treasury yield also climbed as high as 4.687 percent, the highest since January.Higher Treasury yields strengthened the dollar broadly. The dollar index, which tracks the greenback against six major currencies, rose to around 99.43 Wednesday morning, its highest level in about a month.Foreign investors’ heavy selling in Korean equities added further pressure on the won, as offshore investors convert proceeds from stock sales into dollars.Foreign investors net sold 35.42 trillion won ($23.5 billion) worth of Kospi shares from May 1 through Tuesday. On Wednesday alone, they dumped another 2.5 trillion won, dragging the benchmark Kospi down 1.56 percent as of 2 p.m.The benchmark index briefly fell below the 7,100 mark during trading, touching an intraday low of 7,053.84.“Although the selloff in US semiconductor stocks has eased, rising long-term Treasury yields continue to pressure emerging-market equities,” said Min Kyung-won, an economist at Woori Bank.“Heightened uncertainty is also strengthening demand for the dollar even among reserve currencies, meaning emerging-market currencies such as the Korean won are inevitably facing greater pressure,” he said.