# Philadelphia Stock Exchange Semiconductor Index

Type: Company (SOX)

Source: Finance Intelligence Brief — https://getfinancebrief.com/entity/philadelphia-stock-exchange-semiconductor-index
Canonical HTML page: https://getfinancebrief.com/entity/philadelphia-stock-exchange-semiconductor-index

## Timeline

- **2026-09-22**: Semiconductor index rallies 6% — The Philadelphia Semiconductor Index adds 6% over Monday and Tuesday, pushing the Nasdaq 100 to its first record since early June.
- **2026-09-21**: Meta and chip stocks surge — Meta shares jump 11% on Muse optimism, while Arm Holdings gains 17% and Intel and AMD each rally more than 9%.
- **2026-09-15**: Nasdaq 100 drops 1.5% — The Nasdaq 100 completes a two-day decline that erases more than $600 billion in market value.
- **2026-09-14**: AI infrastructure stocks tumble — First trading session after Amodei's essay sees CoreWeave and Lam Research decline more than 9% as investors price lower future AI compute demand.
- **2026-09-12**: Anthropic CEO calls for AI slowdown — Dario Amodei publishes an essay urging slower development of cutting-edge AI models, with backing from Sam Altman and Elon Musk.

## Recent coverage (1 stories)

### AI Stocks Erase $600B in 2 Days, Then Nasdaq 100 Hits Record
2026-09-27 16:05:13 · Sentiment: Neutral · Impact: 5/10 · Sources: 2

AI-exposed stocks experienced a violent two-week reversal as fears of slower model development erased $600 billion in Nasdaq 100 value, only for Meta's Muse-assisted consumer enthusiasm to push the index to a June-record high. The swing shows market risk is concentrated in narrative shifts rather than earnings fundamentals.
Full story: https://getfinancebrief.com/story/ai-whiplash-jolts-stocks-600b-nasdaq-record

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