Micron Technology Inc. (MU) just had its best month in four decades. And if history is any guide, the next one might not be so kind.

The memory-chip maker's stock jumped 87.76% in May, its strongest monthly gain since November 1985, as the artificial-intelligence infrastructure buildout sent memory prices and demand soaring. Shares closed the month near $971, up from roughly $512.

Only one month in Micron's public-market history was better: November 1985, when the stock soared 97%.

But investors celebrating that historic run may soon face a less friendly seasonal backdrop.

Why June Worries Micron Bulls

Over the past 41 years, June has been Micron's poorest-performing month. According to TradingView data, the stock has generated an average June return of -1.35%, the weakest seasonal reading of any month.

Micron has finished June higher in just 54% of years — meaning gains have historically been little better than a coin flip.

The worst June came in 2015, when shares plunged 32.6%. The best arrived only last year, when Micron surged 30.5% in June 2025 — the strongest June performance on record.

Seasonal weakness tends to intensify after mid-month. Data from Seasonax shows that between June 15 and June 30, Micron has posted gains in only 18 of the past 41 years, a win rate of 43.9%. During that period, the stock generated an average return of -1.44%, while the median return was an even weaker -4.89%. The gap between the average and median suggests that a handful of strong years masked what has typically been a challenging stretch for the stock.

In other words, Micron's seasonal headwinds have historically become more pronounced as June progresses.

What It Means for Investors

Seasonality is not destiny, but it can provide useful context after an exceptional rally. Micron enters June following one of the strongest monthly advances ever recorded by a major semiconductor stock, driven by relentless investor enthusiasm for AI infrastructure spending and next-generation memory products.

History suggests the stock may encounter a more difficult trading environment over the coming weeks, particularly in the second half of the month.

Still, there is an important caveat: the current AI-driven cycle has already produced outcomes that few historical comparisons can fully capture. After all, Micron's strongest June on record occurred just last year, during the same AI investment boom that continues to drive demand today.