ILLUMINA, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K

For the fiscal year ended December 28, 2025

or

Commission file number:001-35406

Illumina, Inc.

(Exact name of registrant as specified in its charter)

5200 Illumina Way, San Diego, CA 92122

(Address of principal executive offices) (Zip code)

Registrant’s telephone number, including area code: (858)202-4500

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes þ Noo

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yeso No þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes þ Noo

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes þ Noo

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13a of the Exchange Act. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☑

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐ Noþ

As of February 6, 2026, there were 152.9 million shares (excluding 48.4 million shares held in treasury) of the registrant’s common stock outstanding. The aggregate market value of the common stock held by non-affiliates of the registrant as of June 29, 2025 (the last business day of the registrant’s most recently completed second quarter), based on the closing price for the common stock on The Nasdaq Global Select Market on June 27, 2025 (the last trading day before June 29, 2025), was $9.2 billion. This excludes an aggregate of 57.1 million shares of common stock held by officers and directors and each person known by the registrant to own 10% or more of the outstanding common stock. Exclusion of shares held by any person should not be construed to indicate that such person possesses the power, directly or indirectly, to direct or cause the direction of the management or policies of the registrant, or that the registrant is controlled by or under common control with such person.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s proxy statement for the 2026 annual meeting of stockholders are incorporated by reference into Items 10 through 14 of Part III of this Report.

FORM 10-K

FOR THE FISCAL YEAR ENDED DECEMBER 28, 2025

TABLE OF CONTENTS

See “Form 10-K Cross-Reference Index” within Other Key Information for a cross-reference to the parts and items requirements of the Securities and Exchange Commission Annual Report on Form 10-K.

Consideration Regarding Forward-Looking Statements

This Annual Report on Form 10-K contains, and our officers and representatives may from time to time make, “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Words such as: “anticipate,” “intend,” “plan,” “goal,” “seek,” “believe,” “continue,” “project,” “estimate,” “expect,” “strategy,” “future,” “likely,” “may,” “potential,” “predict,” “should,” “will,” or similar words or phrases, or the negatives of these words, may identify forward-looking statements, but the absence of these words does not necessarily mean that a statement is not forward looking. Examples of forward-looking statements include, among others, statements we make regarding:

•our expectations as to our future financial performance, results of operations, or other operational results or metrics;

•the benefits that we expect will result from our business activities and certain transactions we have completed, or may complete, such as product introductions, increased revenue, decreased expenses, and avoided expenses and expenditures;

•our expectations of the effect on our financial condition of claims, litigation, contingent liabilities, and governmental investigations, proceedings, and regulations;

•our strategies or expectations for product development, market position, financial results, and reserves;

•our ability to successfully implement cost reduction plans in a timely manner and the possibility that costs associated with our cost reduction plans are greater than we anticipate;

•our expectations related to the acquisition of SomaLogic, Inc. (SomaLogic) and certain other assets from Standard BioTools Inc. (Standard BioTools), including the future conduct and growth of the SomaLogic business and the proteomics market and our ability to successfully integrate SomaLogic into our existing operations and SomaLogic’s technology and products into our portfolio;

•our estimate of the cost impact on Illumina of the tariffs announced by the U.S. Government and other countries beginning in April 2025; and

•other expectations, beliefs, plans, strategies, anticipated developments, and other matters that are not historical facts.

Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based only on our current beliefs, expectations, and assumptions regarding the future of our business, future plans and strategies, projections, anticipated events and trends, the economy, and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks, and changes in circumstances that are difficult to predict and many of which are outside of our control. Our actual results and financial condition may differ materially from those indicated in the forward-looking statements. Therefore, you should not rely on any of these forward-looking statements. Important factors that could cause our actual results and financial condition to differ materially from those indicated in the forward-looking statements include, among others, the following:

•our expectations and beliefs regarding prospects and growth for our business and the markets in which we operate;

•the timing and mix of customer orders among our products and services;

•challenges inherent in developing, manufacturing, and launching new products and services, including expanding manufacturing operations and reliance on third-party suppliers for critical components;

•uncertainty regarding the impact of our inclusion on the “unreliable entities list” by regulatory authorities in China;

•any reductions or potential reductions in funding for the National Institutes of Health (NIH), or targeted cancellations by the U.S. federal government of certain grants or contracts, could negatively impact our customers and reduce demand for our products and services;

•the impact of recently launched or pre-announced products and services on existing products and services;

•uncertainty regarding, or potential changes in, diplomatic and trade relationships, for example, as a result of changes in the U.S. government administration;

•risks and uncertainties regarding legal and regulatory proceedings;

•uncertainty regarding the impact of tariffs imposed by the U.S. government and its trading partners in response, other possible tariffs or trade protection measures, import or export licensing requirements, new or different customs duties, trade embargoes and sanctions and other trade barriers, as well as the impact of Illumina’s efforts to mitigate the effect of such tariffs;

•risks associated with contracts or other agreements containing provisions that might be implicated by the divestiture of GRAIL, Inc. (f/k/a GRAIL, LLC) (GRAIL), including our ability to fully realize the anticipated economic benefits of our commercial arrangements with GRAIL and our obligations with respect to contingent value rights (the CVRs) issued by us in connection with the GRAIL acquisition, which may adversely affect us and our business and/or the market value of the CVRs;

•the risk of additional litigation arising against us in connection with the GRAIL acquisition;

•our ability to successfully integrate SomaLogic into our existing operations and SomaLogic’s technology and products into our portfolio;

•the assumptions underlying our critical accounting policies and estimates;

•our assessments and estimates used to determine our expected effective tax rate;

•our assessments and beliefs regarding the outcome of pending legal proceedings and any liability that we may incur as a result of those proceedings, as well as the cost and potential diversion of management resources associated with these proceedings;

•uncertainty, or adverse economic and business conditions, including as a result of slowing or uncertain economic growth, competitive landscape, public health crisis, or armed conflict; and

•other factors detailed in our filings with the Securities and Exchange Commission (SEC), including the risks, uncertainties, and assumptions described in Risk Factors within the Business & Market Information section of this report, or in information disclosed in public conference calls, the date and time of which are released beforehand.

Any forward-looking statement made by us in this annual report on Form 10-K is based only on information currently available to us and speaks only as of the date on which it is made. We undertake no obligation, and do not intend, to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, or to review or confirm analysts’ expectations, or to provide interim reports or updates on the progress of any current financial quarter, in each case whether as a result of new information, future developments, or otherwise.

Available Information

Our annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to those reports are available free of charge on our website, www.illumina.com. The information on our website is not incorporated by reference into this report. Such reports are made available as soon as reasonably practicable after filing with, or furnishing to, the SEC. The SEC also maintains an Internet site at www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that electronically file with the SEC. Copies of our annual report on Form 10-K will be made available, free of charge, upon written request.

Assign, BaseSpace, BeadArray, Bluebee, BlueFuse, BlueGnome, cBot, ChatDNA, Clarity LIMS, CircLigase, COVIDSeq, DesignStudio, DRAGEN, DRAGEN ORA, Emedgene, Enancio, FastTrack, Flow, Fluent Biosciences, Genetic Energy, GenomeStudio, Genomics Suite, Golden Gate, HiSeq, iHope, Illumina, Illumina Connected Analytics, Illumina Propel Certified, Infinium, iScan, iSelect, iSeq, MiniSeq, MiSeq, MiSeq FGx, Nextera, NextSeq, NovaSeq, Partek, Pattern Visualization System, PIPseq, Powered by Illumina, Praxis, Ribo-Zero, SureCell, The Analytical Spreadsheet, TruGenome, TruPath, TruSeq, TruSight, Turning Data Into Discovery, Verifi, Verinata, Verinata Health, VeriSeq, XLEAP-SBS, the pumpkin orange color, and the Genetic Energy / streaming bases design are trademarks or registered trademarks of Illumina, Inc.

“GRAIL,” the GRAIL logos, and other trade names, trademarks, or service marks of GRAIL are the property of GRAIL. The “Galleri” mark and logo are registered in numerous countries including the United States and the United Kingdom. Applications to register the “Galleri” mark and logo, the “GRAIL” mark and the logo, and marks associated with GRAIL are also pending in a variety of countries.

Unless the context requires otherwise, references in this annual report on Form 10-K to “Illumina,” the “Company,” “we,” “us,” and “our” refer to Illumina, Inc. and its consolidated subsidiaries.

Our fiscal year is the 52 or 53 weeks ending the Sunday closest to December 31, with quarters of 13 or 14 weeks ending the Sunday closest to March 31, June 30, September 30, and December 31. References to 2025, 2024, and 2023 refer to fiscal years ended December 28, 2025, December 29, 2024, and December 31, 2023, respectively, which were all 52 weeks.