Are the 3 Newest Members of the $1 Trillion Market Cap Club the Latest Sign of an AI Bubble?

Key Points

• AI-driven demand for high-bandwidth memory has propelled Samsung, SK Hynix, and Micron into the $1 trillion market cap club.
• Samsung and SK Hynix now represent 50% of South Korea's KOSPI market capitalization, raising significant concentration risk for the benchmark index.
• The global HBM shortage is projected to last through at least 2027, with all three major suppliers already sold out of their full-year production capacity.

As the world’s insatiable appetite for artificial intelligence (AI) continues to drive a global memory chip shortage, a handful of companies are experiencing outsized gains so pronounced that they have prompted some investors’ concerns about a looming AI bubble to resurface.

Last month, the number of publicly traded companies in the $1 trillion market cap club grew from 10 to 13.

The first new member came when Samsung Electronics OTCMKTS: SSNLF surpassed the landmark valuation, becoming the second Asian company to do so, following Taiwan Semiconductor Manufacturing Company NYSE: TSM, which crossed $1 trillion in July 2025.

Shortly thereafter, two companies whose stocks have surged over the past year joined the club: Micron Technology NASDAQ: MU and South Korean semiconductor company SK Hynix (which does not trade directly on major U.S. exchanges).

With the memory chip shortage driving this trend projected to endure for at least another year, if not longer, any shock to other facets of the AI trade could have severe consequences for the companies in the high-bandwidth memory (HBM) space.

HBM Demand Is Raising Concentration Risk for South Korea’s Stock Market

Shares of SK Hynix have gained more than 1,000% over the past year, making Samsung’s gain of more than 458% over the same time pale in comparison. Their combined market caps now stand at nearly $2.5 trillion.

As of May 27, those two companies together now account for an unprecedented and deeply concerning 50% of the entire market capitalization of South Korea’s benchmark Korea Composite Stock Price Index (KOSPI). For context, at the end of May, the Magnificent Seven accounted for roughly one-third of the S&P 500.

By itself, that degree of concentration risk is worrisome. But adding a layer of extreme AI-driven and increasingly codependent revenue growth compounds those concerns.

To demonstrate how precipitous that growth has been, Samsung saw overall revenue grow by nearly 37% from 2018 to 2025. However, its Device Solutions division—the firm’s business unit responsible for its global semiconductor and component operations—has seen revenue grow by more than 95% just since 2023.

investor flows tied to short- and long-term trends in HBM can have an outsized effect on the broader index. That concentration means HBM-driven inflows or outflows can disproportionately influence the performance of the other 836 companies in the benchmark.

Metrics Suggest Micron Is Financially Healthy and Still Undervalued

Despite a nearly 1,000% gain over the past year, Micron is trading at a trailing 12-month price-to-earings (P/E) ratio of about 45 and a forward P/E ratio of around 17.

That makes the stock cheap by most Wall Street standards, regardless of its incredible run-up in price since the start of April 2025, when it was trading for just around 1,400% less than what shares are changing hands for today.

Meanwhile, the company's debt-to-equity (D/E) ratio undergirds that contention. Generally, a D/E ratio below two indicates a company with financial stability and conservative management. The S&P 500’s average D/E ratio is 0.65, while Micron’s is only 0.13.

That, among other factors, has kept Micron in analysts’ good graces. The 39 analysts currently covering MU have given the stock a consensus Buy rating.

UBS, for example, recently issued a structural upgrade, raising its one-year price target for Micon from $535 to a Wall Street high of $1,625.

The central argument is that Micron is forecast to generate over $400 billion in free cash flow from 2027 to 2029.

But from an earnings per share (EPS) perspective, there are reasons to be concerned. After EPS contracted by nearly 169% in 2023, it grew by more than 113% in 2024 and over 984% in 2025 despite revenue growth slowing from nearly 62% in 2024 to around 49% in 2025.

That’s largely attributable to the company’s record margins, though. Micron’s guidance projects gross margin targets of an unheard of 81%, with Q2 adjusted free cash flow having reached $6.9 billion.

For Now, the Memory Chip Shortage Has Legs

The global HBM deficit is projected to last at least through 2027, with many forecasts indicating it could stretch into the 2030s.

While the recent performances of Samsung, SK Hynix, and Micron leave the companies looking ripe for a correction, the macro reality suggests the trend is sustainable based on the extent of the supply shortage.

Together, those three companies supply an estimated 95% of the world’s memory chips. And despite it still being the first half of 2026, all three companies have said their production capacity for the entire year is already sold out, meaning they can charge a premium for their products, further expanding their margins.

SK Hynix’s management has warned that a HBM wafer shortage could last as long as five years. And all three companies have pivoted production to satisfy existing demand, leaving shortages for consumer electronics (e.g., laptops and smartphones), which are experiencing supply constraints and price hikes.

Much of that is being driven by hyperscalers like Alphabet NASDAQ: GOOGL, Meta Platforms NASDAQ: META, and Microsoft NASDAQ: MSFT, which have secured much of the HBM production capacity through long-term contracts with Samsung, SK Hynix, and Micron.