Micron stock has surged 53.1% on AI server demand, but investors must weigh whether the memory-chip maker's record profits signal a permanent shift in the business or a cyclical peak.

What happened: Micron's revenue grew 196.3% year-over-year to $23.9 billion（約3.8兆円） in its most recent quarter, with DRAM and NAND revenues jumping 207% and 169% respectively. Management says it can only fulfill about "50% to two-thirds" of what key customers are requesting, and the company is planning capital spending "above $25 billion（約4兆円）" in fiscal 2026, with construction-related spending alone expected to "increase by over $10 billion（約1.6兆円） year over year" in fiscal 2027.

Why it matters: The stock now trades at a price-to-earnings ratio of 47.7—nearly double the S&P 500's 24.1—implying the market believes AI has permanently transformed memory from a cyclical commodity into a critical strategic asset. However, Micron's history shows severe volatility: the stock fell 50% during the 2022 inflation shock (double the S&P 500's 25% decline), 43% in the 2020 pandemic crash, and 88% in the 2008 financial crisis. The options market is currently pricing in an implied volatility of 94, in the 94th percentile, suggesting traders expect continued large price swings.

What to watch: The durability of Micron's new strategic customer agreements—the company has recently signed its "first five-year SCA"—will signal whether this cycle is genuinely different. If these long-term contracts prove protective during a downturn, they could indicate a structural change; if not, the large capital spending plan risks creating tomorrow's supply glut if AI demand moderates.