Meta Muse AI Agent Tops App Store, Sending AMD to Trillion-Dollar Club and Nasdaq to Record

A wave of AI enthusiasm swept through markets on Monday, September 21, after Meta Platforms launched its Muse personal AI agent, which quickly climbed to the top spot on Apple's App Store. Meta shares surged more than 11% on the day, boosted further by Wells Fargo raising its price target on the stock. The rally was fueled by the view that Muse signals robust and durable consumer demand for AI products, reinforcing confidence that the broader AI build-out remains on track.

The excitement radiated across the chip sector. Advanced Micro Devices jumped 10%, crossing a $1 trillion market capitalization for the first time, joining Nvidia in that exclusive club. Intel gained 12%, Arm Holdings climbed 17%, and the Philadelphia Semiconductor Index rose 4.3% for its fifth consecutive gain. The iShares Semiconductor ETF closed nearly 5% higher. The Nasdaq Composite closed at a record 30,618, up 0.29% on the session.

Looking ahead, investors are monitoring the AI angle in upcoming U.S.-China trade talks, with analysts noting that any movement on chip export restrictions or technology access could meaningfully sway Nvidia shares in either direction. Meanwhile, some market observers flagged that the AI rally is creating challenges for diversified portfolios and cautioned that Tuesday's session showed early signs of investors pulling back rather than chasing Monday's gains, suggesting momentum could be fragile if near-term catalysts disappoint.