Kospi jumps 4.47% on Aug. 5, triggering buy-side circuit breaker

South Korea's stock market swung violently between gains and losses after the Kospi's Aug. 5 surge to 6,598.26, when foreign investors bought a net 1.4514 trillion won and the benchmark briefly rose as much as 4.96% to 6,674.66, triggering a buy-side circuit breaker. On Aug. 6, the reversal deepened into a sell-side circuit breaker as intraday losses accelerated under simultaneous foreign and institutional selling, while the Kosdaq tried to turn positive, reinforcing expectations that market leadership may be broadening beyond large semiconductor names. Market participants said the latest pullback followed an unusually strong rebound and may represent a near-term pause rather than a decisive trend change. Recent trading has shown less concentration in Samsung Electronics and SK Hynix, with money spreading into healthcare, K-content and other small- and mid-cap growth stocks. Over the two weeks from July 22 to Aug. 4, the Kospi fell 5.8% and the electrical and electronics sector dropped 9.5%, while the KRX 300 Healthcare Index rose 6.5% and the K-Content Index gained 2.7%. The Kosdaq has also rebounded sharply. After jumping 11.63% on July 31, it rose for four consecutive sessions through Aug. 5 for a cumulative gain of 24% and triggered buy-side circuit breakers for three straight sessions, described as unprecedented. Mirae Asset Securities analyst Kim Seok-hwan said it was only the third time since the Kosdaq's 1997 launch that the index had risen more than 20% over three sessions, after the 2000 U.S. IT bubble and the 2008 global financial crisis. Investors are balancing supportive external factors, including falling oil prices and a steadier won tied to expectations for a Strait of Hormuz reopening, against pressure from hawkish comments by Federal Reserve governors. Within semiconductors, debate over peak NAND flash prices, weaker-than-expected SanDisk earnings guidance and speculation over a possible U.S. listing for SK Hynix's NAND unit Solidigm have weighed on sentiment, although a Reuters report that Samsung Electronics and SK Hynix are exploring expanded shareholder returns has offered a potential offset. Cosmetics shares including APR have rallied on strong earnings and overseas revenue growth, adding to expectations for a more earnings-driven and rotational market.