随着2026年的开启，全球市值最高的公司在股市中的根基正显露出动摇迹象。 自10月29日创下历史新高以来，英伟达(NVDA.US)股价已累计下跌9.1%，表现远逊于标普500指数。这反映出投资者日益担忧人工智能(AI)支 出的可持续性，以及这家芯片巨头的市场主导地位。 近期的下跌尤为引人注目。回顾收盘价刷新历史纪录当日，英伟达股价较2022年底涨幅已超过1300%，公司市值突破5万亿美元，较不到三年 前的约4000亿美元大幅跃升。然而如今，短短数月内其市值已蒸发4600亿美元，致使三年累计涨幅收窄至近1200%。 与此同时，这家占据主导地位的AI芯片制造商正面临前所未有的激烈竞争，对手不仅包括AMD(AMD.US)等同行，甚至还有其最大的客户——如 谷歌(GOOGL.US)和亚马逊(AMZN.US)等。更令华尔街忧心的是，英伟达对多家客户的投资行为，可能被解读为通过人为手段提振需求。 "风险显然已经上升，"资产管理规模达1300亿美元的Advisors Capital Management合伙人兼投资组合经理JoAnne Feeney评论道。 如果英伟达继续延续这一颓势，将对大多数股票投资者产生影响。汇编数据 ...

Core Viewpoint - Citigroup has significantly reduced its holdings in major AI-related technology stocks, reflecting concerns over the sustainability of the AI investment boom and the potential for a market correction in these high-valuation stocks [3][9]. Summary by Category Holdings Overview - As of September 30, 2025, Citigroup's total market value of holdings reached approximately $224 billion, up from $204 billion in the previous quarter, marking a 10% increase [1][2]. - The firm added 826 new stocks and increased holdings in 1,833 stocks, while reducing positions in 3,028 stocks and completely selling out of 399 stocks [1][2]. Major Stock Adjustments - Citigroup has notably reduced its positions in major tech giants such as Nvidia, Microsoft, Apple, and Amazon, aligning with the narrative of an "AI bubble" and the subsequent market correction [3][9]. - Despite the reductions in tech giants, Citigroup slightly increased its stake in Broadcom, indicating a positive outlook on its ASIC technology growth prospects [3][4]. Top Holdings - Nvidia remains Citigroup's largest holding with approximately 33.39 million shares valued at about $6.23 billion, although this represents a 28.22% decrease from the previous quarter [6]. - The second-largest holding is the Russell 2000 Index ETF put options, with around 23.99 million shares valued at approximately $5.81 billion, reflecting a 12.26% increase [4]. - Microsoft ranks third with about 9.56 million shares valued at approximately $4.95 billion, down 19.55% from the previous quarter [4]. Strategic Moves - Citigroup has increased its holdings in put options for the Nasdaq 100 Index ETF by 81%, indicating a preparation for potential declines in AI-related stocks [7][8]. - The top five purchases in the third quarter included high-yield corporate bond ETF put options and Nvidia put options, emphasizing a strategy to hedge against potential downturns in the AI sector [8]. Selling Trends - The top five sell-offs included Nvidia, Meta, Amazon, Microsoft, and Apple, further underscoring Citigroup's cautious stance on the AI investment landscape [9].