美国科技股最大的风险是：日本国债

Group 1 - The core concern is the potential normalization of Japan's bond yields, which could pose a significant threat to U.S. tech stock valuations, especially if real yields rise substantially by 2025 [1][3] - BCA Research highlights that from 2019 to 2022, U.S. tech stock valuations were perfectly synchronized with U.S. real bond yields, but by the end of 2022, they began to correlate with Japanese government bonds, which are the last to have negative real yields [4][6] - The high valuations of U.S. tech stocks are not solely based on domestic liquidity but also rely on the low-cost funding environment provided by Japan [6][7] Group 2 - Current changes in Japan's domestic economy, with long-term inflation expectations nearing the 2% target, indicate that the pressure for normalization of the Bank of Japan's monetary policy will gradually increase [6] - BCA warns that if Japan's real bond yields normalize, the global liquidity environment will tighten, directly impacting tech stocks that depend on low-cost funding [7]