Material Event (Form 8-K)

On June 5, 2026, Santander Holdings USA, Inc. (the "Company") completed the public offer and sale of $1,000,000,000 aggregate principal amount of its 5.040% Fixed-to-Floating Rate Senior Notes due 2030 (the "2030 Notes"), $750,000,000 aggregate principal amount of its 5.220% Fixed-to-Floating Rate Senior Notes due 2032 (the "2032 Notes") and $750,000,000 aggregate principal amount of its 5.701% Fixed-to-Floating Rate Senior Notes due 2037 (the "2037 Notes" and, collectively with the 2030 Notes and the 2032 Notes, the "Notes"). The Notes were issued pursuant to a Senior Debt Indenture, dated as of April 19, 2011 (the "Senior Debt Indenture"), between the Company and Deutsche Bank Trust Company Americas, as trustee (the "Trustee"), as amended by an Eighth Supplemental Indenture, dated as of March 1, 2017 (the "Eighth Supplemental Indenture"), between the Company and the Trustee and as supplemented by a Thirty-Seventh Supplemental Indenture, dated as of June 5, 2026 (the "Thirty-Seventh Supplemental Indenture"), between the Company and the Trustee. The Notes were sold pursuant to an underwriting agreement, dated as of June 2, 2026 (the "Underwriting Agreement"), between the Company and Santander US Capital Markets LLC, BofA Securities, Inc., Citigroup Global Markets Inc., J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and RBC Capital Markets, LLC, as representatives of the several underwriters listed therein.

The Underwriting Agreement, the Senior Debt Indenture, the Eighth Supplemental Indenture, the Thirty-Seventh Supplemental Indenture and the Notes are more fully described in the prospectus supplement filed with the Securities and Exchange Commission (the "Commission") on June 4, 2026 to the accompanying prospectus filed with the Commission on December 15, 2023 as part of the Company's Registration Statement on Form S-3 (File No. 333-276089) (the "Registration Statement").

The Underwriting Agreement, the Senior Debt Indenture, the Eighth Supplemental Indenture, the Thirty-Seventh Supplemental Indenture and the form of the Notes are attached to this Current Report on Form 8-K as Exhibits 1.1, 4.1, 4.2, 4.3, 4.4, 4.5 and 4.6, respectively, and are incorporated into this Item 8.01 by reference. The foregoing descriptions of the Underwriting Agreement, the Senior Debt Indenture, the Eighth Supplemental Indenture, the Thirty-Seventh Supplemental Indenture and the form of the Notes do not purport to be complete and are qualified in their entirety by reference to the exhibits attached hereto.

This Current Report on Form 8-K is being filed, in part, for the purpose of filing the attached documents as exhibits to the Registration Statement in connection with the issuance of the Notes, and such exhibits are hereby incorporated by reference into the Registration Statement.