Santander Holdings USA, Inc.

This Current Report on Form 8-K is being filed in connection with the completion on August 20, 2026 (the “Closing Date”) of the previously announced acquisition of Webster Financial Corporation, a Delaware corporation (“Webster”), by Banco Santander, S.A., a Spanishsociedad anónima (“Banco Santander”), pursuant to a transaction agreement dated February 3, 2026 (the “Transaction Agreement”), by and among Banco Santander, Webster and a wholly-owned subsidiary of Webster incorporated in the State of Virginia (“Webster Virginia”).

Among other things, the Transaction Agreement provides for the merger of Webster with and into Webster Virginia, with Webster Virginia continuing as the surviving corporation in such merger transaction (the “Reincorporation Merger”), and, immediately afterwards, the acquisition by Banco Santander of all outstanding shares of Webster Virginia common stock through a statutory share exchange, all subject to the terms and conditions of the Transaction Agreement (the “Share Exchange” and, together with the Reincorporation Merger, the “HoldCo Transactions”).