Why Illumina (ILMN) Stock Is Sinking Today

What happened

Shares of gene-sequencing company Illumina (ILMN) plunged 19.3% on Friday, to $234.23 as of 2:51 p.m. ET, after third-quarter results that beat profit estimates but left investors worried about how fast the business is growing. Illumina reported after the close on Thursday.

Revenue was $1.13 billion, up 4.2% year on year, and adjusted earnings per share were $1.44, the company said in its results release. Investing.com and GuruFocus both reported that the profit figure beat analysts’ estimates.

Illumina said healthy clinical demand and placements of its NovaSeq X sequencers drove results above its own guidance. It raised its 2026 forecast to revenue of $4.64 billion to $4.66 billion and diluted earnings per share of $5.40 to $5.45.

Why it matters

The stock went into the report priced for more. It had more than doubled this year and closed Thursday 1.2% below its 52-week high, so a beat and a modest raise weren’t enough. Investing.com said the beat masked growth concerns, and StockStory, via Yahoo Finance, reported that sales fell short of analysts’ estimates.

Illumina’s fourth-quarter forecast calls for revenue of $1.22 billion to $1.24 billion, according to the release. Management said it will give its full 2027 outlook with fourth-quarter results, which leaves investors without a view on next year for now.

What the market is telling us

Illumina’s shares moved 5% or more on 21 of the last 252 sessions, so a drop this size is rare for the stock. Before Friday it was up 121.2% this year, and at Thursday’s close of $290.06 it sat 1.2% below its 52-week closing high of $293.69 from 5 October 2026. $1,000 invested in Illumina five years ago would have been worth $712 at Thursday’s close.

We read Friday’s fall as the price of a big run meeting single-digit growth: the quarter was fine, but 4% revenue growth doesn’t support a stock that had doubled. The 2027 guidance in the new year is the next real test.