Banco Santander, S.A. (the "Bank" or "Banco Santander"), in compliance with the Securities Market legislation, hereby communicates the following:

OTHER RELEVANT INFORMATION

Reference is made to our notice of inside information of 19 February 2024 (official registry number 2114)  (the "Buy-back Commencement Communication"), relating to the buyback programme of own shares (the "Buy-back Programme") approved by the Board of Directors of Banco Santander.

Pursuant to article 5 of Regulation (EU) no. 596/2014 on Market Abuse of 16 April 2014, and articles 2.2 and 2.3 of Commission Delegated Regulation (EU) 2016/1052, of 8 March 2016, the Bank informs of the transactions carried out over its own shares between 8 and 16 May 2024 (both inclusive).

The cash amount of the shares purchased to 16 May 2024 as a result of the execution of the Buy-back Programme amounts to 1,016,672,584 Euros, which represents approximately 69.7% of the maximum investment amount of the Buy-back Programme. The programme was announced together with its other characteristics through the Buy-back Commencement Communication.

Issuer name: Banco Santander, S.A. - LEI 5493006QMFDDMYWIAM13

Reference of the financial instrument: ordinary shares - Code ISIN ES0113900J37

Detailed information of the transactions carried out within the referred period is attached as Annex I.

Boadilla del Monte (Madrid), 17 May 2024

ANNEX I

Detailed information on each of the transactions carried out within the context of the Buy-back Programme between 08/05/2024 and 16/05/2024 (both inclusive)