Chip stocks slide as bubble warnings follow historic Q2 rally

Semiconductor stocks opened the second half of 2026 under heavy selling pressure on Wednesday, as bubble warnings from Bank of America ↘ 3.62% and the Bank for International Settlements rattled investors following a quarter in which three chipmakers alone added $2 trillion in market value.

A Reckoning After Record Gains

The selloff caps the Philadelphia Semiconductor Index's PHLX Semiconductor Sector Index ↘ 12.13% best quarter ever — a roughly 74% surge in Q2 driven by investors broadening their artificial intelligence bets beyond Nvidia ↘ 9.26%. Micron Technology ↘ 17.46% rose more than 240% during the quarter, adding roughly $920 billion in market capitalization. Intel ↘ 10.33% jumped 216%, adding approximately $480 billion, while Advanced Micro Devices ↘ 17.26% nearly tripled, adding about $615 billion in value.finance.yahoo+2

The magnitude of the rally drew comparisons to the dot-com era. Bank of America's proprietary Bubble Risk Indicator — which scores assets on a scale of zero to one — stands at 0.91 for the PHLX Semiconductor Sector and 0.82 for the broader Technology Select Sector, according to Reuters. The Buffett Indicator, comparing total U.S. stock market capitalization to GDP, reached 218% in the first quarter, just shy of its all-time high.reuters

Central Banks Add to the Alarm

The timing compounds jitters already stirred by the Bank for International Settlements, which warned in its annual economic report published June 29 that "excessive" spending on AI data centers risks a financial meltdown. The BIS noted that the five largest hyperscalers are projected to spend more than $1 trillion on AI infrastructure in 2025 and 2026, drawing explicit parallels to the dot-com crash and 19th-century railway mania.fortune+2

Taiwan Semiconductor Manufacturing ↘ 10.78%, which hit a 52-week high on the final trading day of Q2, also fell as broader Asia-Pacific markets remained under strain. The VanEck Semiconductor ETF ↘ 11.21%, which tracks the sector, had risen 71% in Q2 — its best quarterly performance since its inception in 2000.macrotrends+1

Stretched Valuations Meet Rising Rates

The pullback arrives amid a challenging macro backdrop. Money markets are now nearly fully pricing in a Federal Reserve rate hike by September, with inflation still running above 4%. The S&P 500 price-to-sales ratio sits at 3.22, well above its long-term average of 1.84, according to LSEG. Bank of America strategists have issued eight separate warnings to clients in 2026 urging them to prepare for a summer correction, noting that seven of the bank's ten historical bear-market signposts are now flashing red.finance.yahoo+3