Here's a fun puzzle: artificial intelligence demand is through the roof, everyone needs more chips, and semiconductor stocks are rallying. So why are some of the biggest names in the business just... sitting there?

That's the divergence Bernstein analyst Stacy Rasgon is pointing out. The AI boom is very real—companies and labs are reporting rapidly growing revenues, and demand for computing power shows no signs of slowing. But the stock market's reaction has been, well, a bit lopsided.

"The industry faces a clear shortage of computing power," Rasgon told CNBC on Friday. He pointed to rising memory prices and tight supply across the entire AI ecosystem, from the chips themselves to the optics and CPUs that support them.

So you'd think all chip stocks would be flying, right? Not quite.

Rasgon notes that while companies like Intel Corp. (INTC) and Advanced Micro Devices, Inc. (AMD) have surged recently, others have been relatively stagnant. We're talking about the heavyweights of the AI world: NVIDIA Corp. (NVDA) and Broadcom Inc. (AVGO).

What gives? It turns out investors aren't just buying "AI." They're buying scarcity. Rasgon says money has rotated into the areas facing the tightest supply constraints—think memory and semiconductor equipment. That's created a split in sector performance where the suppliers are getting more love than some of the flagship AI chip designers.

This has led to a pretty interesting valuation gap. Rasgon highlights that companies like NVIDIA and Broadcom appear to be trading at around 15 times earnings or less. Meanwhile, the stocks of their suppliers—the companies making the stuff they need—are surging to much higher multiples.

That kind of imbalance, where the companies fueling the AI engine trade cheaper than the companies selling them the fuel, probably won't last forever. Rasgon suggests the gap between different parts of the AI supply chain will eventually correct "one way or the other." Either the suppliers come down, or the big AI players catch up.

In Monday's premarket session, the action was down across the board, according to market data. Shares of Nvidia fell 1.24% to $199.18, Broadcom declined 1.40% to $400.86, Intel slipped 1.24% to $67.65, and Advanced Micro Devices dropped 1.09% to $275.35.

So the story here isn't just "AI is hot." It's that even in a red-hot market, there are winners, laggards, and a valuation disconnect that someone, eventually, is going to have to fix.