Coherent fell 28% on CoreWeave's debt scare, not its order book: AI lasers sold out through 2027

Coherent▼−6.03% — Coherent, down 6.03 percent today fell 28% over the past month and Lumentum▼−5.67% — Lumentum, down 5.67 percent today 13% ¹, and the fear came from someone else's balance sheet. Yields of roughly 15% or more on some CoreWeave▼−4.67% — CoreWeave, down 4.67 percent today bonds this month spread the scare to anything attached to AI infrastructure ³. Bernstein, the Wall Street research firm, keeps Outperform, its buy-equivalent rating, on both suppliers, and reads the slide as broad de-risking across AI stocks, not deteriorating module fundamentals ¹. On Bernstein's reading, backed by the order books, the market priced a financing problem into a shortage.

The order books say the sellers priced the wrong risk

The scarcity itself is old news on this page: Lumentum sold out to 2029, and so was Nvidia's $2 billion into Coherent while insiders sold ². What is new is the supplier's own voice, two weeks from the print. Coherent's chief technology officer, Julie Sheridan Eng, told the PECC Summit, an optical-industry conference, on October 20↗ that its indium phosphide, the laser material underneath AI interconnects, is essentially sold out through the end of 2027, with expansion underway ².

Bernstein's model gives the print a mark to hit: revenue of $2.4 billion against a $2.3 billion consensus, earnings of $2.05 a share against $1.99, and December-quarter guidance of $2.613 billion against $2.547 billion ¹. Its targets are $350 for Coherent, which reports on November 4, and $1,220 for Lumentum, which reports the next day ¹⁴.

The scarcity propping the price is also the weak point

The trade turns on whether indium phosphide stays scarce, not on CoreWeave's credit. Bernstein's Asia supply checks↗ put the scale-up market, optics linking chips inside one rack-scale machine rather than between racks, at roughly six times today's pluggable market, assuming per-Gbps pricing that holds flat, an assumption the bears dispute ¹.

Scarcity already carries a price tag: Lumentum's advanced 200G lasers sell at roughly double the prior generation's price on Deutsche Bank's reading↗ ⁵. Coherent's roadmap runs the same way: near-packaged engines, optics socketed beside the processor, deploy from 2027, and optical links between processor and memory arrive toward the decade's end ².

The November 4 call has to answer the margin question

Two things break the bull case: VCSELs, a cheaper rival laser family, diverting demand, or new indium-phosphide supply landing, and Bernstein says the debate will not be settled on next month's calls ¹. The print still has to answer the margin question: gross margin near 41%, and management quantifying the 6-inch wafer ramp investors say has yet to appear in it ¹.

The call can also update PhotonLink, Coherent's co-packaged-optics platform, which counts more than ten customer engagements with first revenue due in the December quarter ⁴. If the print lands, whoever sold the drawdown pays; until new supply or VCSELs arrive, the two suppliers hold the pricing power.