当前AI泡沫究竟多大？瑞银：本轮泡沫比TMT时期更具“合理性”，三大见顶信号尚未出现

Core Viewpoint - UBS believes that while the current US stock market exhibits seven conditions indicative of a bubble cycle, the "reasonableness" of the current AI bubble far exceeds that of the 2000 period, and key peak events have yet to occur [1][3]. Group 1: Bubble Characteristics - UBS identifies three key signals that typically indicate a bubble peak: extreme valuations, long-term overheating catalysts, and short-term peak events, which are currently absent [1][2]. - The current market perceives a 20% probability of a bubble, emphasizing the need for investors to understand key signals that may indicate a bubble burst [2]. Group 2: Valuation Analysis - UBS notes that the current valuations in the AI sector are not extreme, with the price-to-earnings (P/E) ratio of major tech companies at 35 times, significantly lower than the bubble levels seen in previous cycles [9][12]. - The equity risk premium (ERP) is currently around 3%, indicating that the market has not completely ignored risks due to excessive optimism [12]. - The potential market for semiconductors is deemed reasonable, with projections suggesting that by 2030, semiconductor spending could reach 1.3% of global GDP, up from approximately 0.7% [12][15]. Group 3: Macro Risk Structure - The macroeconomic risk structure has fundamentally changed since the 2000 internet bubble, with the US government currently facing higher debt-to-GDP ratios and significant fiscal deficits compared to the past [5][7]. - The "weak government, strong corporate" dynamic may lead investors to shift funds from nominal assets to real assets, thereby supporting higher stock valuations [7]. Group 4: Long-term Catalysts - There are currently no signs of excessive investment or leverage that typically precede a bubble burst, with ICT investment as a percentage of GDP remaining below the peak levels of 2000 [18][21]. - The capital expenditure to sales ratio for major tech companies is supported by strong cash flows rather than debt, contrasting sharply with the high debt levels seen during the internet bubble [21][24]. Group 5: Short-term Peak Events - UBS highlights that no significant short-term peak events have occurred, such as large-scale mergers and acquisitions that characterized the peak of the internet bubble [28][31]. - Current earnings momentum for tech stocks remains strong, and price momentum has not reached extreme levels, indicating that the market is not yet at a peak [32][34]. Group 6: Future Considerations - UBS warns that potential bubbles may exist within the tech sector, particularly in the semiconductor industry, where high profit margins could face pressure due to increasing capital intensity and competition [36].