U.S. stocks fell for a third straight session on the 18th, with technology and semiconductor shares leading the decline as Treasury yields climbed and oil prices strengthened. The Dow Jones Industrial Average closed down 116.38 points, or 0.22%, at 53,343.40, the S&P 500 lost 53.30 points, or 0.69%, to 7,691.76, and the Nasdaq Composite dropped 355.20 points, or 1.33%, to 26,289.71. Chipmakers were hit hardest, with the Philadelphia Semiconductor Index plunging 628.54 points, or 4.98%, to 11,992.46 after having risen 1.64% a day earlier. Investors faced a sharp rise in long-term borrowing costs, with the U.S. 30-year Treasury yield reaching 5.34% intraday and the 10-year yield hovering around 4.70%, a backdrop that tends to weigh on high-growth sectors by reducing the present value of future earnings and raising the cost of capital spending. Memory-chip names and semiconductor ETFs saw especially heavy losses, while Nvidia, AMD, Broadcom, ASML, Intel, Lam Research, Applied Materials and TSMC ADR all fell. Analysts also pointed to fading enthusiasm for AI hardware after a strong rally and to concerns that spending by major technology companies may be running ahead of visible returns. Defensive sectors including healthcare, energy and some financials helped cushion the broader market, supported in part by oil prices near two-week highs. Market participants now expect the contest between rising bond yields and technology valuations to remain a key driver in the near term.