HBM (high-bandwidth memory) market crashes: Micron, SK Hynix, and SanDisk stocks plunge ~30% on oversupply and weakening AI/server demand, signaling major component supply glut.

The artificial intelligence boom has created one of the broadest rallies the semiconductor industry has experienced in decades. Graphics processors grabbed the headlines first, but the scramble to build AI infrastructure quickly spread to networking, optical components, power equipment, cooling systems, and memory. Every piece of the AI supply chain suddenly mattered because hyperscalers were racing to deploy capacity faster than suppliers could manufacture it.

Few industries benefited more than memory. High-bandwidth memory (HBM), enterprise SSDs, and data-center storage all became bottlenecks, allowing suppliers to command premium pricing while investors rewarded them with premium valuations. That combination produced eye-popping stock gains.

Now the same forces that fueled the rally are beginning to work in reverse, raising an uncomfortable question for investors: Has the AI memory boom merely paused, or has the cycle already begun turning lower?

Those declines look painful in isolation. Surprisingly, they also demonstrate just how extraordinary the previous rally had become. Even after losing one-third to one-half of their value, most companies still trade hundreds of percentage points above where they began the AI memory run. SK Hynix's experience illustrates how quickly sentiment has changed. After pricing its U.S. IPO at $149 per share, the stock opened at $170 and climbed to nearly $195 within days. Since then, it has unraveled, recently falling below $137—about 8% beneath its IPO price and roughly 30% below its post-debut high.

The original AI memory thesis rested on one simple fact: there was not enough supply. HBM production sold out years in advance as AI accelerator demand exploded. According to Micron, SK Hynix, and Samsung Electronics, virtually every major producer committed capacity well before wafers entered production. That shortage is beginning to ease. Manufacturers have expanded HBM capacity aggressively while NAND and DRAM production continues to increase. At the same time, China's ChangXin Memory Technologies (CXMT) just held a widely anticipated IPO that could fund another wave of domestic memory expansion, increasing competitive pressure over the coming years.

The market is already discounting that future. South Korea's KOSPI index has fallen roughly 29% over the past month, officially entering bear market territory after a sharp sell-off, including an approximate 11% decline in a single day. Because memory manufacturers represent such a large share of Korea's technology sector, the weakness has rippled throughout global semiconductor stocks. The selling has not stopped with memory. NVIDIA has fallen roughly 17% from recent highs while Taiwan Semiconductor Manufacturing has declined about 20%, suggesting investors are reassessing AI infrastructure valuations more broadly.

Memory has always been among the semiconductor industry's most cyclical businesses. Shortages eventually become oversupply, pricing falls, profits compress, and valuations follow. Granted, today's AI demand remains far stronger than previous PC or smartphone cycles. HBM demand should continue growing for years as next-generation AI systems require more memory per GPU. That said, stock prices often peak well before earnings do. Even after their corrections, many memory companies continue trading at valuation multiples that assume years of elevated profitability. If supply expands faster than demand, estimates may still prove too optimistic.

In short, the AI memory story is not broken—but the easy money likely has already been made. The sector ran far ahead of fundamentals as shortages pushed pricing and investor expectations to unusual levels. Now capacity additions, new competition from China, and the memory industry's long history of boom-and-bust cycles are pulling valuations back toward reality. Patient investors should resist the temptation to view every 30% or 40% decline as a bargain. The long-term AI tailwinds remain intact, but history suggests memory stocks rarely bottom after the first leg down. Regardless of how attractive the industry looks over the next decade, smart investors may find better entry points if this correction continues to play out.