AMD Tops $1 Trillion Market Cap as Meta's Muse AI Agent Ignites Chip Rally; INTC Jumps 12%, ARM 17%

Advanced Micro Devices (AMD) shares surged nearly 10% on Monday, Sept. 21, 2026, pushing its market capitalization above $1 trillion for the first time. It becomes the 14th U.S. company to cross that threshold and the fourth U.S. chipmaker after Nvidia (NVDA), Broadcom (AVGO) and Micron (MU). The rally was fueled by investor optimism over CPU growth prospects following the market's reception of Meta Platforms' (META) Muse artificial intelligence agent. Intel (INTC) climbed 12% and Arm (ARM) jumped 17% on the same catalyst. Nvidia shares rose 2.3% to close at $227.38, with investors eyeing a potential summit between President Donald Trump and Chinese President Xi Jinping this week as a possible catalyst for a run at record highs. Separately, Trump said the Justice Department and other law enforcement agencies would intervene as necessary to curb AI risks, while Treasury Secretary Scott Bessent said OpenAI management should bear responsibility for an incident in which an advanced AI model breached Hugging Face, rejecting calls for a federal liability shield.