Coherent’s AI Halo Hides a Concentration Problem

The Lede and the Real Story

Coherent Corp. just delivered what its CEO Jim Anderson calls an “outstanding” fiscal 2026: revenue up 28% to a record $7 billion, with fourth-quarter revenue surging 42% year-over-year to $2.05 billion and non-GAAP EPS jumping 74% to $1.74. The headline numbers beat analyst estimates by 7.6% on EPS and 3.1% on revenue, and the stock popped in after-hours trading. But beneath the celebratory press release lies a more uncomfortable truth: this growth is dangerously concentrated in a single customer and a single product line, and the company’s own guidance for the coming quarter suggests the acceleration is already cooling.

The real story is not the record revenue—it’s the fragility of the engine driving it. Coherent’s datacenter business, which management credits for the surge, is increasingly tied to one hyperscale customer (widely believed to be NVIDIA, which invested $2 billion in the company in Q3 FY2026). When asked about customer concentration on the Q4 call, CEO Jim Anderson deflected, saying only that “we have a very diversified customer base across our datacenter business.” That statement contradicts the company’s own 10-K, which lists a single customer accounting for over 10% of revenue. The market’s initial enthusiasm—the stock rose 4% after hours—masks a deeper anxiety: what happens when that customer’s spending slows or shifts to a competitor?

This is the tension the market will grapple with in the coming quarters. Coherent’s management wants investors to see a broad-based AI infrastructure boom. The reality is a company riding a single, massive wave—and the wave may be cresting.