经济学家眼中全球经济增长所面临的最大不确定性是什么？

Group 1 - The global economic growth forecast has been cautiously optimistic, with the International Monetary Fund adjusting its growth prediction from an average tariff rate of 24% to 17% for the U.S., indicating the significant impact of U.S. tariff policies on global growth in 2025 and 2026 [2] - The uncertainty surrounding the U.S. tariff policies includes potential legal challenges and the possibility of additional tariffs on specific industries such as semiconductors and pharmaceuticals, which could significantly impact regions like Singapore and Taiwan if tariffs reach 25% [2] - The imposition of a 40% tariff on goods exported to the U.S. via Vietnam by former President Trump introduces further uncertainty for Chinese companies' international strategies [2] Group 2 - The unpredictability of U.S. policies, including immigration, tariffs, and monetary policy, poses significant risks to the economy, with potential inflation and stagnation concerns arising from labor shortages and rising domestic product prices [3] - The recent decision by the Federal Reserve to lower interest rates may reduce the attractiveness of U.S. dollar assets due to decreasing real yields, prompting investors to diversify their global asset allocations [3] - The potential for asset bubbles is a major concern for investors, although it is premature to declare that assets are fully inflated, as companies like Nvidia and Apple continue to show accelerating profit growth and substantial cash flow [4] Group 3 - Chinese technology companies have seen their valuations decrease as their profit growth has outpaced stock price increases, leading to lower valuations compared to earlier in the year [4] - The ongoing transition between old and new technologies is expected to create new investment expectations, with a high probability of asset bubble formation in a liquidity-rich environment [4] - Investors are encouraged to seize current investment opportunities amidst these dynamics [4]