Samsung Electronics and SK hynix gained in premarket trading despite a sharp rise in U.S. Treasury yields, as expectations for expanding AI infrastructure investment and higher memory prices supported semiconductor stocks. At 8:20 a.m. on the 30th, Samsung Electronics was at 276,500 won, up 4,000 won, or 1.4%, while SK hynix stood at 1.787 million won, up 22,000 won, or 1.2%, according to Nextrade. The 30-year Treasury yield reached 5.612%, its highest level since June 2002, and the 10-year yield rose to 5.265%, its highest since 2007. Micron gained 1.05%, SanDisk rose 0.98% and SK hynix's American depositary receipts advanced 2.62%, while Nvidia fell 0.72% as investors took profits near its previous high following earlier gains tied to a $150 billion share buyback. Oil prices declined after news that Saudi Arabia would resume crude exports and that the United States and Iran had made diplomatic contact. Brent crude for November delivery fell 3.48% to $89.38 a barrel, while West Texas Intermediate for October delivery dropped 2.56% to $102.59. KB Securities said Samsung Electronics' investment in Helix, a U.S. AI infrastructure company, could broaden the company’s access to data center demand beyond memory supply. Samsung Electronics said the previous day that it and affiliates would invest a combined $1 billion in Helix, including a $500 million contribution from Samsung Electronics. Helix is led by Adam Selipsky, former chief executive of Amazon Web Services, and is developing an integrated data center, power and network infrastructure business. KB Securities expects DRAM average selling prices to rise 15% to 20% quarter-on-quarter in the third and fourth quarters of this year, followed by double-digit gains in the first quarter of next year. It said capacity at the world's three major DRAM makers is effectively sold out through 2028, which could strengthen suppliers' pricing power as AI infrastructure demand expands and prompt a reassessment of the strategic value of Samsung Electronics' memory business.