The US semiconductor sector has achieved historic gains in the first half of 2026, yet this rally has not been shared equally. Leading AI chipmaker NVIDIA has risen only about 7% year-to-date, placing it at the bottom of the Philadelphia Semiconductor Index constituents, creating a stark contrast with the sector's overall exuberance.
As of Tuesday's close, the Philadelphia Semiconductor Index surged 88% in the second quarter, marking its best quarterly performance on record. Its year-to-date gain of 101% positions it for its strongest annual showing since the dot-com bubble of 1999.
In comparison, the Nasdaq 100 Index rose 28% over the same period, and the S&P 500 gained 15%, both significantly underperforming the chip sector. The core driver of this rally has been strong market bets on demand for AI infrastructure.
However, just as the celebration began, the semiconductor index plunged 7.9% last week, its largest weekly drop since April 2025. It then fell as much as 3.2% on Monday before rebounding to close 3.8% higher. This extreme volatility is prompting investors to reassess the sustainability of the advance.
Simultaneously, NVIDIA's relative underperformance reflects a broadening of AI chip demand across a wider range of semiconductor companies. Whether it can regain dominance with its next-generation Vera Rubin hardware has become a key market focus.
Record-Breaking Quarter: Memory Chips Lead, Gains Outpace Broader Market
The biggest winners in this chip stock rally have been concentrated in the memory and storage space.
SanDisk leads S&P 500 constituents with an 857% year-to-date gain. Micron Technology follows with a 300% surge, its market capitalization surpassing $1 trillion to join the ranks of the world's largest US memory chipmakers. Western Digital, Seagate Technology, and the rebounding Intel round out the top five gainers.
Sean Sun, a portfolio manager at Thornburg Investment Management, stated, "We're seeing investors chase the bottlenecks in the semiconductor industry, which currently favors the memory segment and also benefits Intel's recovery as a foundry."
Meanwhile, South Korean memory chip giant SK Hynix is seeking to raise $29.4 billion in the US market, further underscoring the capital appeal of the memory sector.
NVIDIA Falls Behind: AI Chip Demand Broadens, Competitive Landscape Shifts
NVIDIA stands out as the most notable laggard in this rally. As the world's most valuable company and a synonym for AI chips, its roughly 7% year-to-date gain places it last among Philadelphia Semiconductor Index components. Broadcom, with a gain of about 7.9%, also lags far behind the sector.
Analysis suggests the core reason for NVIDIA's underperformance is that massive spending on AI chips is being dispersed to a broader array of semiconductor companies. Competition has expanded from the initial head-to-head battle with AMD to include custom chip designers and CPU specialists like Intel.
Sean Sun explained, "NVIDIA and Broadcom are hitting those bottlenecks; they are not the high-beta names they once were. I think they'll still do fine, but right now investors want greater beta exposure to the strongest themes."
A key market question is whether NVIDIA's next-generation Vera Rubin hardware can establish a sufficiently significant performance advantage to make it the preferred supplier for AI infrastructure again. However, reports suggest that even with impressive performance, large tech companies may be reluctant to become overly reliant on a single supplier, especially as their capital expenditure scales face shareholder pressure.
Mark Haefele, Chief Investment Officer at UBS Global Wealth Management, wrote in a report, "The share price declines of hyperscale cloud companies this month indicate rising pressure from shareholders to justify spending. We acknowledge the risk of a slowdown in capex growth has increased at the margin."
Valuation Divergence: NVIDIA Hits Multi-Year Low, Some Stocks Severely Overextended
While overall sector valuations are notably high, internal divergence is extreme.
The Philadelphia Semiconductor Index currently trades at about 26 times expected earnings, well above its 10-year average of 19 and close to the recent high of 30 set in 2024. In comparison, the Nasdaq 100 trades at 23 times earnings and the S&P 500 at 20.
Within the sector, ARM Holdings Plc trades at over 140 times 12-month forward earnings, and Intel trades around 100 times, both severely overextended by traditional valuation standards.
NVIDIA sits at the other extreme, with a forward P/E ratio of only about 18, its lowest since 2018 and far below its 10-year average of 36. Micron trades at a forward P/E of about 8, which some on Wall Street interpret as a warning sign that revenue and profits may have peaked.
Bloomberg Intelligence data shows analysts are growing more optimistic about chip stock prospects, forecasting 49% earnings growth for the sector in 2027, up from a 35% expectation in April. Revenue growth expectations have also been raised from 29% to 37%, both significantly outpacing S&P 500 expectations of 17% earnings growth and 7.4% revenue growth.
Heightened Volatility: Retail Influx Coincides with Hedge Fund Retreat
Alongside high returns, chip stock volatility has also hit historic levels.
The Cboe Semiconductor ETF Volatility Index, which tracks expected volatility for semiconductor ETFs, has risen 83% year-to-date. If maintained through year-end, this would be its largest annual increase on record, and it has already reached its highest level since market shocks in April 2025.
This month, the vast majority of trading days have seen the Philadelphia Semiconductor Index move more than 1%, including a single-day maximum gain of 7.9% and an extreme single-day drop exceeding 10%. According to Goldman Sachs prime brokerage data, hedge funds are selling technology, media, and telecom stocks at the fastest pace in a decade, while heavy inflows from retail investors are further amplifying price swings.
CJ Muse, Senior Managing Director and Technology Analyst at Cantor Fitzgerald, said, "New changes in investor composition are exacerbating volatility, while at the same time, there are new AI capability white papers almost every week. We are going to be in this highly volatile market for some time."
He added that the market's biggest current worry is whether hyperscale cloud companies can sustain and expand capital expenditure beyond 2026, though he personally does not believe this "spending spree" will end soon. Currently, Microsoft, Amazon, Alphabet, and Meta all maintain aggressive capital expenditure plans.
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