Scoreboard / ILMN
Illumina, Inc. ILMN
Week of September 18 to September 24, 2026 · Updated September 25, 2026
Setup Snapshot
The Setup in One Card
How ILMN scored, how it moved against the market, and the catalyst behind the move. A high score means the stock deserves research time, not that it is a buy.
Friday Five Score
Weekly Rank
04 of 5
Sector Trend
Improvingup 0.9 percent
Actionability
Extended
Catalyst
Index InclusionIllumina rejoined the S&P 500 before the open on September 21, about 27 months after being removed, following three consecutive earnings beats.
Returns are measured from the Friday, September 18 close to the Thursday, September 24 close. Benchmarks: S&P 500 +0.7% and Nasdaq Composite +1.6% for the week. Benchmark figures are official index closes; sector figures use SPDR sector ETF closes because the official S&P sector index closes for this window were not yet published at press time.
Why It Moved
The Story Behind the Move
Catalyst
S&P Dow Jones Indices announced on September 4, 2026 that Illumina would rejoin the S&P 500 effective before the open on September 21, moving up from the S&P MidCap 400 about 27 months after its June 2024 removal. The shares did not move on the effective day. The 14.31 percent gain came on September 23 and 24, alongside Pacific Biosciences up 15.33 percent, Agilent up 10.46 percent and Mettler-Toledo up 9.11 percent, none of which had an index event.
Why It Mattered
It is the largest and most liquid name in a lab tools pocket that re-rated together, and the index return after 27 months away is a verifiable fact worth a reader knowing. The timing mismatch is published rather than smoothed over.
Risk Note
Index buying is mechanical, finishes in days and adds nothing to earnings. If the move was a group re-rating rather than a company event, it can unwind with that same group for reasons that have nothing to do with this company.
Reader Takeaway
When peers with no share of your catalyst move exactly as much as you do, the catalyst is probably not the explanation. Check what the neighbours did before accepting the story.
Continue the Research
Put ILMN Back in Context
The stock page is one piece of the weekly research. Continue with the original issue, the full public ranking, or the method behind the analysis.
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