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 28 February 2023 (official registry number 1784), 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, that it has carried out the following transactions over its own shares between 12 and 18 April 2023 (both inclusive):

The cash amount of the shares purchased to 18 April 2023 as a result of the execution of the Buy-back Programme amounts to 865,824,661 Euros, which, approximately, represents 94% of the maximum investment amount of the Buy-back Programme which was announced together with its other characteristics through the notice of inside information dated 28 February 2023 (official registry number 1784). Thus it remains pending its execution approximately 6% of such amount.

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), 19 April 2023

ANNEX I

Detailed information on each of the transactions carried out within the context of the Buy-back Programme between 12/04/2023 and 18/04/2023 (both inclusive)