这种集中度扭曲了估值风险和劳动力市场。估值风险不仅在于昂贵的科技股，还在于整体市场的盈利背景可能不如总体数据所显示的那么强劲。在劳动力市场中，典型的扩张会看到强劲的利润推动招聘，但 AI 领域的主要利润获取者并非劳动力密集型。在四月，美国薪资增长与去年同期相比仅为 0.43%，远低于通常伴随经济增长的 1% 至 1.5% 年增长速度。高利润科技集团有限的员工人数增长削弱了总体所得增长，使经济扩张变得日益脆弱，且更加依赖高收入家庭的支出。
这种经济模式在很大程度上受到财富效应循环的支持：上升的 AI 利润推高了股价，从而增强了较富裕家庭的消费能力，在低收入家庭面临实质所得受压榨的同时维持了需求。这种自我维持的循环取决于资本支出保持稳健、股市保持活跃以及富裕消费者继续支出的前提。然而，缺乏广度使得经济高度依赖信心。如果 AI 基础设施的预期回报受到质疑，随之而来的连锁反应可能会引发较弱的财富效应、较疲软的消费，以及最终对美国例外论的广泛重新评估，揭示出美国实力的基础比投资者承认的更为狭窄。
The US economy exhibits diverging indicators as consumer spending and corporate profits near records, while real disposable income and job creation weaken. This anomaly is explained by concentration: growth, profits, capital spending, and market value are heavily clustered within a narrow AI ecosystem (chipmakers, hyperscalers, data centers, infrastructure). The rest of corporate America experiences modest growth or flat performance. Consequently, the US corporate profit share has risen to a record 13.8% of GDP, and net income margins across the broad US equity market have recovered to approximately 9.7%, close to earlier highs. However, this is dominated by a small minority: a handful of AI-linked stocks now account for roughly 40% of the S&P 500's market capitalization.
This concentration distorts valuation risks and the labor market. Valuation risk lies not only in expensive technology stocks but also in the possibility that the broader market's earnings backdrop is less robust than aggregate data suggests. In the labor market, typical expansions see strong profits drive hiring, but the major profit winners in the AI sector are not labor-intensive. In April, US payroll growth was a mere 0.43% from a year earlier, significantly below the 1% to 1.5% annual pace typically associated with a growing economy. This limited headcount growth among high-margin tech groups weakens aggregate income growth, making economic expansion increasingly brittle and dependent on upper-income spending.
This economic model is heavily supported by a wealth effect loop: rising AI profits boost stock prices, which enhances the spending power of wealthier households, sustaining demand while lower-income households face squeezed real incomes. The self-sustaining loop relies on the premise that capital expenditure remains firm, equities stay buoyant, and affluent consumers continue spending. However, the lack of breadth makes the economy highly dependent on confidence. If the expected returns on AI infrastructure are questioned, the resulting fallout could trigger weaker wealth effects, softer consumption, and a broad reappraisal of US exceptionalism, revealing that the foundations of US strength are narrower than investors admit.