Why Is PHLX Semiconductor Index Down 5.86% Today, September 14? AI Slowdown Concerns Hit Chip Spending

The PHLX Semiconductor Index sank 5.86% as AI-safety commentary triggered a reset in expectations for frontier-model pace and, by extension, near-term AI infrastructure capex. The move was broad across key AI-exposed chip names (e.g., NVDA, AMD, AVGO, MU) and accompanied by rotation into software and cybersecurity, indicating repositioning rather than indiscriminate tech de-risking. Technically, SOX weakening below key moving averages signals a fragile near-term setup.