中经评论：美国科技股高波动态势或加剧

Group 1 - The core viewpoint of the articles highlights the volatility in the U.S. tech sector driven by concerns over the sustainability of AI investments and the potential for a market correction in 2026 [1][2][3] - In 2025, the AI investment boom significantly boosted global stock valuations, with the Nasdaq index rising approximately 21% and the market capitalization of major tech companies reaching historical highs, including Nvidia surpassing $5 trillion [1][2] - The concentration of market power among the "seven giants" of U.S. tech, which accounted for over 36% of the S&P 500's total market capitalization, raises concerns about the sustainability of their growth, as capital expenditure growth is projected to decline sharply from 48.8% in 2025 to 18.8% in 2026 [2][3] Group 2 - There is a notable shift in market dynamics, with funds moving from large-cap tech stocks to small-cap and cyclical sectors, indicating a transition from valuation expansion to profit verification [1][2] - The debt risk associated with tech giants is increasing, with AI-related borrowing comprising about 30% of the net issuance of U.S. investment-grade bonds, and this trend is expected to continue into 2026 [3] - U.S. tech companies are expanding into emerging markets like Latin America to leverage energy cost advantages and market growth, although this also exposes them to geopolitical and compliance risks [4]