SAN DIEGO, Sept. 4, 2026, 6:14 p.m. EDT — Illumina, Inc. NASDAQ:ILMN gained an estimated $704 million in after-hours market value Friday. The shares rose 2.1% to $222.88 after S&P Dow Jones Indices said the gene-sequencing company will return to the S&P 500.
The headline sounds larger than the market’s verdict. Illumina had fallen 1.6% during regular trading. The index rally left the stock only 0.5% above Thursday’s close.
- Illumina will join the S&P 500 before trading opens on Sept. 21.
- The stock reached $224.28 at 5:36 p.m. EDT, then surrendered part of the jump.
- Friday’s late price implies a preliminary equity value of about $33.65 billion.
- That equals roughly 7.3 times Illumina’s 2026 revenue-guidance midpoint.
S&P announced the rebalance at 5:15 p.m. EDT. Illumina will replace Builders FirstSource, Inc. NYSE:BLDR in the benchmark. The change becomes effective before the Sept. 21 open.
The S&P news erased Friday’s loss
Illumina after-hours trades, Sept. 4, 2026
Source: Yahoo Finance. Latest observation at . After-hours prices can change quickly.
A round trip through the mid-cap index
The return carries some history. GoDaddy Inc. NYSE:GDDY replaced Illumina in the S&P 500 in June 2024. Illumina moved into the S&P MidCap 400 as it prepared to separate Grail.
Now Illumina is moving back up. Funds that track the S&P 500 will need to align their holdings around the effective date. S&P did not disclose Illumina’s final index weight or the number of shares those funds may buy.
The value estimates use Illumina’s 151.0 million shares outstanding on July 24. Employee issuance, repurchases or other transactions may have changed that count. The calculations are therefore preliminary.
The after-hours gain mostly repaired the day
Preliminary equity-value bridge using 151.0 million shares
The operating recovery now carries a fuller price
Illumina’s latest quarter gives the promotion a business backdrop. Revenue rose 9.5% to $1.159 billion. GAAP operating margin improved to 21.1% from 20.2% a year earlier.
Cash conversion was less tidy. Free cash flow fell to $162 million from $204 million. Operating cash flow declined to $201 million from $234 million.
Management raised its 2026 revenue range to $4.60 billion through $4.64 billion. It also lifted non-GAAP earnings guidance to $5.30 through $5.40 a share. Both measures come from the company and are not GAAP forecasts.
“Demand for NovaSeq X remains high,” Chief Executive Jacob Thaysen said in the July 30 earnings release. He tied that demand to broader workflows and multiomics capabilities.
Better growth, less valuation room
Latest operating data and the late after-hours price
At $222.88, the stock trades around 41.7 times the midpoint of that adjusted earnings outlook. It also stands 34.3% above the $166 average target in Benzinga’s 19-analyst set. That average includes targets set before the latest rally.
Views remain wide. Benzinga lists 11 Buy ratings, six Holds and two Sells. Argus raised its target to $235 from $180 on Thursday, leaving much less upside from Friday’s late quote.
What shareholders face before Sept. 21
The immediate catalyst is mechanical demand. The longer test is commercial. Investors need NovaSeq X demand and margin gains to outrun a valuation already above the analyst average.
Risks: Index-related buying can fade after funds rebalance. China restrictions, tariffs and product-order timing may also disrupt revenue. Thin after-hours trading can exaggerate a price move.
Illumina’s S&P return restores a place lost two years ago. It does not restore cheapness. Friday’s modest net gain suggests investors saw both sides.
