通膨预期正在推动资产再配置：债券对富裕投资者而言已不再有吸引力，机构投资者对债务的配置降至四年低点，富裕个人则降至历史低点。现金也不是有效的通膨对冲；相较之下，股票在需求强劲或价格上升时更具韧性。不过，这也意味著消费支撑更集中于高净值族群，而所谓 K 型经济 可能在股市转弱时，迅速拖累美国消费。
风险点在于市场高度依赖少数大型 AI 股。Nvidia 将公布财报，其市值约 5.4 兆美元，为全球最大公司；所谓 Magnificent 7 约占 S&P 500 市值的三分之一。若富裕投资者开始收紧支出，只有真实现金流支撑估值的消费品、服务与汽车等类股可能承压，进一步让 S&P 500 更依赖远期现金流的 AI 驱动公司，使涨势更加脆弱。
US equities remain powered by tech giants and AI, but fund flows show investors are nearly fully committed. Two Bank of America surveys found institutional cash allocations fell by the biggest monthly amount in two years, while equity allocations posted the largest monthly jump on record; cash now equals 3.9% of assets. Private clients—those with at least $3mn in investable assets, for whom BofA manages $4.5tn—also hold under 10% in cash, the lowest since the survey began.
Rising inflation expectations are driving the shift. Bonds look less attractive, with debt allocations at a four-year low among institutions and a record low among wealthy individuals, while cash is a weak inflation hedge. Equities can be more resilient when inflation is demand-led. Yet US consumption is heavily supported by the wealthy, so a K-shaped economy may mask weakness until markets falter and even rich households trim spending.
The main vulnerability is concentration in a few AI-led megacaps. Nvidia, with a market value of about $5.4tn, reports earnings, and the Magnificent 7 account for roughly one-third of the S&P 500’s market capitalisation. If wealthy investors pull back, stocks that need actual cash flows—consumer goods, services, and autos—could be compressed further, leaving the index even more dependent on long-dated AI value and making the rally more fragile.