South Korea's KOSPI opened down 1.35% at 6,759.95 on August 21 after long-term U.S. Treasury yields resumed their climb, following a nearly 6% surge the previous day. It later pared losses to 6,780.37 by 9:26 a.m. The KOSDAQ fell 3.64% to 810.25, putting the 810 level at risk. Overnight declines on U.S. markets, renewed concerns about the fiscal deficit and Treasury supply, and disappointing Walmart earnings pressured equities. Foreign and institutional investors sold South Korean shares, while retail investors bought. Semiconductor stocks diverged as Micron's $10 billion, 10-year AI memory investment plan lifted its shares and supported SK Hynix. Analysts said foreign flows, shareholder-return expectations and the absorption of overhead supply would shape the market's next moves.