The Philadelphia Semiconductor Index tumbled 7.9% on Tuesday, a decline that was more than five times the S&P 500's 1.44% loss, as weakness in memory chip stocks overshadowed broader market moves. The selling pressure was particularly acute in names tied to high-bandwidth memory (HBM), a critical component for AI processors, sparking concerns that the AI-driven rally may be losing steam.
Micron Technology fell 13%, Sandisk dropped 14%, and Western Digital slid 8.5%, each declining more than Nvidia's 4.1% loss. Advanced Micro Devices, Intel, and Marvell Technology also saw losses ranging from 5.8% to 9.4%. The Philadelphia Semiconductor Index's plunge was about 3.5 times the Nasdaq's 2.21% decline and roughly 5.5 times the S&P 500's drop.
The selloff was concentrated in memory and storage stocks, which have become a direct proxy for AI server demand. High-bandwidth memory is essential for AI processors to handle large datasets, and when investors question AI spending, these stocks tend to swing more sharply than Nvidia itself. The Roundhill Memory ETF, which had hit a record high on Monday, fell about 12%, according to Investopedia. The fund, with $23.4 billion in assets, is heavily weighted toward SK Hynix, Samsung, and Micron, which together make up nearly three-quarters of its holdings.
The impact was felt globally. South Korea's KOSPI index closed down 9.99%, its largest drop in over three months, as shares of Samsung Electronics and SK Hynix both fell more than 12%, triggering a 20-minute trading halt. Samsung and SK Hynix now account for more than half of the KOSPI's market value, according to Reuters.
Analysts pointed to heightened volatility and retail-driven trading. "Volatility has blown out," said Alexander Redman, chief equity strategist at CLSA, noting that "retailers are in the driving seat" and flagging risks from margin use and leveraged single-stock ETFs. Ross Mayfield, investment strategy analyst at Baird, described the trade as "highly concentrated and flow-driven," making it vulnerable to shifts in sentiment. Thomas Martin at Globalt added that new headlines around AI "raises questions about all the spending" on capacity and capital expenditure.
Pressure shifted to New York after Asian markets tumbled. The Washington Post reported that the Nasdaq fell 2.4% at the open and the S&P 500 dropped 1.6%, following a near 4% slide in Japan's Nikkei and almost 2% off Hong Kong's Hang Seng.
Micron is set to report fiscal third-quarter results on June 24 after the bell, with an analyst call at 6 p.m. EDT. The company's guidance is closely watched because it is embedded in the memory pricing chain. Micron shares extended losses even after the company announced a strategic deal with Anthropic on memory and storage architecture, supply, AI adoption, and a new investment in Anthropic's Series H round. "AI has permanently elevated the role of memory," said Sumit Sadana, chief business officer at Micron.
Tuesday's selling could be driven by traders exiting crowded bets rather than a fundamental hit to demand. Micron may still talk up tight HBM supply and strong AI orders, and softer inflation data could ease rate hike fears. However, the risk is that Micron signals memory prices are peaking, and if tighter Fed policy persists, the same funds and indexes that drove AI names higher could continue pulling money from the supply chain. LSEG data, cited by Reuters, shows traders now see higher odds of a second Fed hike by December, with PCE inflation data due Thursday.
