Inside the AI Rally That Just Produced the Best Momentum Trade in 35 Years

The AI Companies and Market Indicators Driving the Record Run

The rally is visible across market capitalizations and geographies, but its gravitational center remains a handful of mega-cap tech firms and the increasingly broad ecosystem of suppliers, cloud providers, and enterprise adopters feeding the AI buildout.

The Magnificent Seven and Mega-Cap Leaders

NVIDIA crossed a $5 trillion market capitalization this spring, while Samsung breached $1 trillion as Asian chipmakers continued to ride a wave of AI infrastructure spending . Microsoft, Alphabet, Amazon, and Palantir all remain central to the investment narrative. Alphabet, for instance, received a price-target upgrade to $420 per share from Stifel analyst Mark Kelley following stronger-than-expected Q1 2026 earnings, with the analyst naming it a top sector pick .

The so-called Magnificent Seven — Alphabet, Amazon, Apple, Meta, Microsoft, NVIDIA, and Tesla — now represent 34.8% of the S&P 500, according to BlackRock's Investment Institute . Their collective earnings revisions over the last two quarters rank among the top five strongest in any cycle since 1988, matched only by the dot-com era and the post-pandemic surge .

AI Infrastructure: The Best-Performing Stocks of 2026

If you look past the household names, some of 2026's best-performing stocks are companies supplying the physical infrastructure behind artificial intelligence. Under Morningstar's coverage, five names lead the charge: flash memory provider SanDisk surged approximately 464.5%, with its share price rocketing from roughly $34 to over $1,500. Bloom Energy, Intel, Western Digital, and Seagate round out the top performers — all integral to the AI supply chain .

Zacks Investment Research highlights equally startling short-term gains. Micron Technology posted an 82% 12-week price change, while Flex (FLEX) surged 110% over the same period. The scale of those moves reflects both the enormous demand for AI compute and the sheer weight of money chasing the theme .

Broadening Beyond a Narrow Tech Trade

Despite the concentration in a handful of mega-cap names, the rally has spread meaningfully across sectors. Tickeron's trending list tracks 26 AI-linked stocks across 9 distinct industries — a signal that the bull market's engines now extend beyond semiconductors and cloud software into enterprise adoption and supply-chain infrastructure . Man Group, the quantitative hedge fund, has observed that stocks with the strongest price trends are clustering heavily in AI and technology, and that the "wedge" between price performance and sentiment is almost entirely explained by industry effects — meaning AI isn't just a factor in the momentum trade; it is the momentum trade .

The Risks That Could Unravel the Rally

For all the earnings strength, analysts see two primary vulnerabilities: historically extreme positioning in the most popular stocks, and the growing risk that inflation — partly fueled by tariffs on imported goods — forces the Federal Reserve to tighten monetary policy.

100th Percentile Crowding: The Most Concentrated Trade in 30 Years

In a research note that rippled through trading desks, JPMorgan strategist Dubravko Lakos-Bujas warned that the rush into high-beta, momentum-driven stocks — including Palantir, Coinbase, and NVIDIA — has reached the "100th percentile" of crowding, the most extreme positioning the bank has recorded in three decades . The note described the concentration as "a red flag for the broader market" and a sign of rising short-term complacency.

The crowding dynamic has created a self-reinforcing feedback loop. Citadel's quant chief describes a "new market paradox": the more widely AI-powered tools are adopted by investors, the more likely those tools are to identify the same factors, narratives, and risk signals, converging on the same trades. When dozens or hundreds of sophisticated funds are training models on similar earnings transcripts, macro data, and filings, the output can cluster dangerously — making crowded trades a defining risk of the modern hedge fund ecosystem .

In April, this fragility was already showing. Momentum stocks had outperformed globally by 17–22%, but extreme greed signals and crowded positioning had created what one analysis called "inflection risk" — a high probability that the trade would break violently when sentiment shifted .

Tariff-Driven Inflation and the Fed Tightening Risk

While investors focus on AI earnings, the macroeconomic backdrop has deteriorated. U.S. headline inflation was projected to rise from 2.7% toward 3.4% in the first quarter of 2026 as the costs of aggressive tariffs increasingly shift from retailers to consumers . By January, the Producer Price Index had already risen 0.5% against a 0.3% forecast; Core PPI jumped 0.8%, more than double market expectations .

Aberdeen's analysts warned that the full impact of tariffs on prices had not yet peaked, expecting the effect to intensify through early 2026 before easing later in the year . Meanwhile, the Official Monetary and Financial Institutions Forum cautioned that aggressive tariff hikes are generating revenue but are increasingly flowing through to consumer prices, eroding real spending power through mid-2026 .

The combination of sticky inflation and geopolitical shocks — notably the Iran conflict, which sent oil prices higher and contributed to intermittent AI stock selloffs in April and May — has forced the Federal Reserve to signal caution on further rate cuts . Markets in late 2025 had priced roughly 75 basis points of additional cuts through the end of 2026; that expectation now looks optimistic . If inflation stays sticky and the Fed reverses course, momentum stocks trading on long-duration cash flows would be among the hardest hit.

Geopolitical and Policy Wildcards

Other risks compound the picture. The conflict with Iran and the resulting leap in crude oil prices — Brent crude was up from roughly $70 per barrel before the war — worsened U.S. inflation readings in early 2026 . South Korea's Kospi index tumbled 2.3% from its all-time high in May on concerns the government might redistribute AI profits to citizens, demonstrating how quickly policy surprises can rattle AI-exposed markets .

Meanwhile, Michael Burry, the investor known for betting against the housing bubble before 2008, has warned that the current market resembles the dot-com era — characterized by AI dominance, a disconnect from economic fundamentals, and a capital-expenditure shift from buybacks to massive AI investments that removes a traditional source of support for stock prices .

Five Factors That Will Determine Whether the Streak Continues

Goldman Sachs captured the stakes in a May 2026 research note: the trajectory of the momentum trade and the S&P 500 will be dictated by the macroeconomic backdrop and the outlook for AI investment . Analysts across firms point to five specific factors that will make the difference between a continued rally and a sharp reversal.

1. AI Earnings Delivery vs. Expectations

The rally's fundamental underpinning is the belief that enormous AI capex will translate into commensurate revenue growth. If that doesn't happen — if AI infrastructure spend doesn't show up in earnings — the bubble risk rises sharply. Goldman Sachs warned specifically that a downturn in AI capital expenditure or an equity and bond volatility spike could trigger a "catch down" reversal .

2. The Inflation and Fed Policy Trajectory

Tariff-induced price increases, combined with AI-driven demand for chips, energy, and infrastructure, are feeding a uniquely modern inflation dynamic. If it persists, the Federal Reserve may be forced to halt or reverse the rate-cutting cycle, directly threatening the high-valuation, long-duration stocks at the center of the momentum trade . Money managers cited by Channel News Asia said as early as January 2026 that AI-driven inflation was the "most overlooked risk" of the year for exactly this reason .

3. Crowding Unwinds and Liquidity Cascades

The more capital that piles into the same trades, the less room there is for error. If the momentum factor breaks, the concentration of capital could trigger cascading liquidations. The fact that JPMorgan's crowding metric sat at the 100th percentile as of mid-2025 and conditions have only tightened since then leaves historically little cushion . Hao Hong, CIO at Lotus Asset Management, predicted in May that "the momentum story will persist for another few months, with significant volatility in between, till it finally sees a climax" — and that if inflation expectations continue to run hot, the climax would come sooner .

4. Geopolitical Stability

The Iran conflict and rising oil prices have already pulled markets off their highs multiple times in 2026 . Any further escalation — particularly one that compounds the existing inflation headwinds — would directly threaten the AI trade.

5. The Breadth of the Rally

The bull market has spread beyond the Magnificent Seven into AI infrastructure and supply-chain names, which is, in theory, a healthy sign of a maturing cycle . The critical test will be whether that broadening continues or whether the rally narrows back into a handful of over-owned names. If breadth stalls, it will signal that capital is retreating to the most congested trades — a pattern that historically precedes reversals.

For investors, the message from analysts is not that the AI trade is doomed, but that the margin for error has narrowed to historic lows. The same forces delivering extraordinary returns are now creating extraordinary risk, and the path forward will be determined not by whether AI is transformative — it is — but by whether the macro and positioning realities allow the rally to breathe.