Semiconductor Mania: Is the AI Rally Overheated, or Just Getting Started?

Over the trailing six months, the iShares Semiconductor ETF (SOXX) is up 113%, including a 100% gain just since March 30^th more than triple the 37% gain in the iShares MSCI USA Momentum Factor ETF (MTUM) and far outpacing the 10% return of the iShares Core S&P 500 ETF (IVV) over the same stretch. The Roundhill Magnificent Seven ETF (MAGS), by contrast, is actually down 3% over the same six months.

Six-month total return: semiconductors vs. momentum, the S&P 500, and the Magnificent Seven
Source: YCharts. Data as of June 30, 2026.

Those numbers tell a story that’s easy to miss in the headlines: this isn’t simply another “Magnificent Seven” rally. It’s a much narrower, much more intense move concentrated specifically in semiconductors, due to massive data center capital expenditures, which have led to widespread memory chip shortages that have sent hardware profits into overdrive.

The question every investor should be asking is straightforward: is this overbaked, or is it sustainable?

Two forces of money

We think today’s market is best explained by a tug-of-war between two types of investors: momentum and fundamentals.

Momentum investors are trying to match indexes or simply keep up with the AI thematic rally. They’re not primarily concerned with the merits of any individual investment — they’re focused on the story and the price action. Fundamental investors, by contrast, evaluate the quality and prospects of a business and are often deeply concerned with the price they pay to own it.

Interestingly, the two camps take turns winning. On up days, momentum tends to carry the day. On down days, fundamentally oriented investments tend to hold up better while momentum-driven positions give back gains. That push-and-pull is a useful signal of just how fragile a narrow, explosive rally can be.

Going forward, momentum investors are making an implied bet that the recent past repeats itself. Fundamental investors, whether they realize it or not, are betting on change. That divide has real risk management implications — explosive, unanimous trends have historically not ended well, even when the underlying story (AI-driven demand for chips) is genuinely powerful.

FOMO has returned, and it’s narrow

We wrote about the return of FOMO as semiconductor and AI-related names took over headlines earlier this year, and that theme has only intensified. Investors’ general fear of losing money has increasingly been replaced by something more specific: the fear of not keeping up. That’s a very human response when winning is this good. But investors will face a multitude of market environments and leadership shifts over an investing horizon, and few of them will look like this one.

The S&P 500^® Index gained roughly 14% for the quarter, while Large Cap Growth stocks — the more direct beneficiary of the AI and semiconductor trade — gained closer to 20%, depending on the index. Semiconductor-specific exposure more than tripled even that pace. This is a rally within a rally.

How we’re thinking about it

Rather than trying to call the top or bottom of the semiconductor trade, we think the more useful question is one of risk. It all depends on what the real risk is to an investor: not making enough money, or the potential for losing it. Portfolios built to capture explosive, narrow trends can look brilliant right up until the trend reverses — and reversals in unanimous, crowded trades tend to be sharp.

Our approach favors funds and strategies that can participate in genuine earnings-driven strength without depending entirely on it continuing. That’s a different posture than chasing the trade, but it’s one built to hold up across more than just this particular quarter.