ILMN: Other company developments

Item 8.01. Other Events. On August 10, 2026, Illumina, Inc. (“Illumina”) entered into an Underwriting Agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC and Citigroup Global Markets Inc., as representatives of the several underwriters named therein, for the issuance and sale by Illumina of $300,000,000 aggregate principal amount of its 4.950% notes due 2029 (the “Notes”). The offering is expected to close on August 17, 2026, subject to customary closing conditions. Illumina expects to use the net proceeds from the offering, together with cash on hand, to repay its 4.650% notes due September 9, 2026. The Notes will be issued and sold pursuant to a Registration Statement on Form S-3 (Registration No. 333-281921) under the Securities Act of 1933, as amended, that Illumina filed with the Securities and Exchange Commission (the “SEC”) on September 4, 2024. Illumina is filing the Underwriting Agreement as part of this Current Report on Form 8-K for purposes of such Registration Statement. The description of the Underwriting Agreement set forth above is qualified by reference to the Underwriting Agreement filed as Exhibit 1.1 to this Current Report on Form 8-K and incorporated herein by reference. Item 9.01. Exhibits. Exhibit Number Description of Exhibit 1.1 Underwriting Agreement, dated August 10, 2026 between Illumina and J.P. Morgan Securities LLC and Citigroup Global Markets Inc., as representatives of the several underwriters named therein 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Date: August 12, 2026 ILLUMINA, INC., By