South Korea's KOSPI index opened lower on the 16th as rising international oil prices and U.S. Treasury yields kept investors cautious. The index started at 6,611.24, down 16.02 points, or 0.24%, from the previous trading day, before attempting a modest rebound around the flat range. Its lower boundary near 6,600 appeared relatively well-supported. Foreign and institutional investors were net sellers, while other corporations and individuals were net buyers, reportedly purchasing shares of Samsung Electronics and SK Hynix. U.S. stocks had fallen broadly in the previous session, while the U.S. 10-year Treasury yield climbed above 5%, its highest level in 19 years, reducing demand for risk assets. International oil prices exceeded $100 a barrel amid worsening Middle East geopolitical tensions, with Saudi Arabia notifying some European customers of delayed crude deliveries, raising concerns about prolonged supply disruptions and inflation. Technology shares showed relative resilience as debate over an AI speed-control theory continued and sentiment toward the sector stabilized somewhat. The Philadelphia Semiconductor Index edged higher, although Samsung Electronics and SK Hynix remained stalled. Funds moved into secondary battery-related stocks including LG Energy Solution and POSCO International. The KOSDAQ, South Korea's tech-heavy secondary market, opened at 808.37, down 4.04 points, or 0.50%, and fell about 0.7% in early trading, with biotechnology and robotics stocks broadly weaker.