美银：AI开启政府背书的“新泡沫时代”，繁荣与崩盘将成常态

Core Insights - The market is entering an unprecedented "bubble era" characterized by rapid alternation between prosperity and recession, driven by extreme expectations surrounding AI technology [1] - Historical patterns show that major technological leaps have consistently led to large-scale asset bubbles, with the current AI revolution being supported by government initiatives [1][2] - The report indicates that while the market shows typical bubble characteristics by 2025, core U.S. tech stocks have not yet reached extreme instability levels seen during the 1990s internet bubble [1] Government Support and Bubble Dynamics - Historical connections exist between major technological changes and asset bubbles, with past examples including the railway stocks in the 19th century and the tech bubble of the late 1990s [2] - Unlike previous bubbles, the current AI bubble benefits from strong government backing, which provides ample funding and higher policy tolerance, extending the bubble's growth cycle [5] - Geopolitical competition has intensified countries' commitments to AI, further reinforcing the bubble's resilience [5] Market Volatility and Expectations - The current market volatility is attributed to the "expectation gap" surrounding AI technology, where the promise of transformative change contrasts with the slower-than-expected realization of that change [6] - This expectation gap leads to frequent swings in market sentiment between extreme optimism and cautious skepticism [6][7] - The volatility driven by technological expectations is more sudden and rapid compared to traditional market cycles, rendering conventional forecasting models ineffective [7] Bubble Risk Indicators - Bank of America has developed a bubble risk indicator based on four key asset price characteristics: returns, volatility, momentum, and fragility [8] - A notable feature of this indicator is that volatility increases as prices rise, contrary to typical market behavior, indicating potential extreme positions driven by fear of missing out (FOMO) [8] - While the overall U.S. stock market and core tech stocks have not shown typical bubble instability, certain segments are already exhibiting bubble characteristics [11] Unique Risks and Market Concentration - The current AI bubble faces unique risks due to its unprecedented scale, with market concentration at historical highs, exemplified by Nvidia's market cap exceeding that of any European country [20] - If Nvidia were to be valued at the peak P/E ratio of Cisco in 2000, its market cap could reach $20.8 trillion, highlighting the potential for significant market corrections based on forward earnings expectations [22] - Predictions suggest that AI spending could reach $3-4 trillion annually by 2030, with long-term estimates reaching $5 trillion, but there are concerns about the overestimation of AI's productivity potential [22] Investment Strategy Recommendations - The report suggests a counterintuitive investment strategy during bubble periods: diversification may increase risk, while concentrated holdings in leading assets combined with cash hedges are recommended [23] - Historical data indicates that assets at the forefront of bubbles tend to outperform until the bubble bursts, making diversification a risky approach [23] - The report also notes that during previous bubbles, the center of the bubble often outperformed global markets, which may contradict the notion of an impending peak in the "American exceptionalism" theme by 2025 [25] Conclusion on Market Outlook - While timing the market remains challenging, the eventual bursting of the AI bubble appears inevitable, with tightening financial conditions identified as a significant risk factor [27] - High volatility is expected to persist, keeping the market fragile, while ongoing debates about AI's future will continue to elevate uncertainty and instability [27]