Most megacap tech stocks weakened

U.S. stocks closed lower across all three major indexes overnight as volatility in semiconductor shares flared again, Samsung Securities said on Aug. 19.

Treasury yields edged down but remained elevated, keeping investors on guard, Samsung Securities analyst Seo Jeong-hoon wrote. International oil prices were also slightly higher, reflecting tensions in the Middle East.

President Donald Trump said in a social media post that no negotiations with Iran were taking place and that none were planned. Earlier, however, Kushner, Trump's son-in-law who is serving as a Middle East envoy, said talks with Iran were still underway and had made more progress than ever.

The S&P 500 fell 0.69%, while the Dow Jones Industrial Average lost 0.22%. The tech-heavy Nasdaq dropped 1.33%, and the Philadelphia Semiconductor Index tumbled 4.98%.

Memory-related stocks were hit particularly hard. Micron fell 7.02%, Sandisk dropped 9.01%, and SK Hynix's American depositary receipts slid 9.20%. The iShares MSCI South Korea ETF, which trades in the U.S. under the ticker EWY and tracks the MSCI Korea Index, sank 8.13%.

By sector, energy led gains with a 1.79% rise. Health care and consumer staples also advanced more than 1%, while information technology, industrials and materials underperformed.

Most megacap technology stocks also stayed under pressure, Samsung Securities said. Meta Platforms fell 4.45% as a large damages trial continued in federal court in California over the legality of its social media service operations. Nvidia lost 2.34%, while SpaceX fell 1.98%.

Amazon was little changed, while Alphabet and Microsoft posted modest gains. Apple, which Seo said has stepped back from the race to ramp up AI investment, rose 1.45%.

Baidu fell 12.73% after reporting weaker-than-expected results. In contrast, Alibaba, which Seo said is viewed as ahead in building AI capabilities in China, rose 2.76% in New York trading.

Kang Kyung-ju, Hankyung.com reporter, qurasoha@hankyung.com