全球资本对美国的高度集中已显失衡。美国约占全球上市股指权重的三分之二、私人资本资产的一半和全球债券市场的约 40%，却仅占全球人口的约 4%、全球增长的 10%、全球贸易的 13% 和按购买力平价计算的约 15% 的全球 GDP。这种集中在过去十多年加剧：外国投资者对美股敞口增至 20 万亿美元以上，多数未对冲；但美元约 10% 的回落已将汇率顺风转为逆风，叠加估值偏高与集中度上升，使风险收益比恶化。

推动美股超额表现的结构性顺风正在消退。自金融危机以来，利率长期下行、企业税率近乎减半、量化宽松以及利润份额上升，共同推高估值。美联储研究显示，低利率与低税率解释了过去三十年美国利润增长的近一半。如今，集中风险显著：过去三年，7 家公司贡献了标普 500 总回报的 55%，前 10 只股票占指数 40%。同时，美国债务率攀升、政策不确定性上升，动摇了美债“无风险”假设，促使机构减少对美债配置。

资本再平衡已启动且影响巨大。挪威主权财富基金 2.2 万亿美元资产中 53% 在美国，若降至 40% 仍属高配，也将释放约 2,500 亿美元流向他处。新去向主要在新兴与发展中经济体：过去十年贡献了全球三分之二以上的增长；印度每年新增劳动力逾 1,200 万；其劳动生产率增速约 3%，是发达经济体的三倍以上。相较之下，这些市场公共债务更低、政策更稳、相关性更弱，既提高预期回报，又降低组合风险，标志着一次必要且持久的全球资本再平衡。

Global capital has become excessively concentrated in the US. America accounts for roughly two-thirds of global equity benchmarks, about half of private capital assets, and around 40% of global bond markets, yet only about 4% of the world’s population, 10% of global growth, 13% of trade, and roughly 15% of global GDP on a purchasing-power-parity basis. Over the past decade, foreign exposure to US equities rose to more than $20 trillion, mostly unhedged; but a roughly 10% dollar decline has flipped a currency tailwind into a headwind, while elevated valuations and concentration have worsened risk-adjusted returns.

The structural forces behind US outperformance are fading. Since the financial crisis, a long decline in interest rates, a near-halving of corporate taxes, quantitative easing, and a rising profit share boosted valuations; Federal Reserve research suggests lower rates and taxes alone explain nearly half of profit growth over the past three decades. Now concentration risk is acute: just seven companies delivered 55% of S&P 500 returns over the last three years, and the top 10 represent 40% of the index. Rising debt ratios, policy uncertainty, and challenges to central-bank independence are also undermining Treasuries’ “risk-free” status, prompting rotation away from US fixed income.

Rebalancing has begun and its effects are large. Norway’s $2.2 trillion sovereign wealth fund holds 53% in US assets; cutting that to 40% would free roughly $250 billion for deployment elsewhere. The prime destinations are emerging and developing economies, which generated more than two-thirds of global growth over the past decade; India alone adds over 12 million workers annually, and developing-world productivity growth near 3% is more than triple that of advanced economies. With lower correlations, improving policy credibility, and higher expected returns, these markets offer genuine diversification and signal a necessary, durable shift in global capital allocation.