Banco Santander, S.A., in compliance with the Securities Market legislation, hereby communicates the following:

OTHER RELEVANT INFORMATION

Reference is made to our notice of inside information of 6 October, 2021 (official registry number 1086), relating to the buyback programme of own shares (the "Buy-back Programme") approved by the Board of Directors of Banco Santander, S.A. 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, Banco Santander, S.A. informs -on the basis of the information received from Morgan Stanley Europe SE as intermediary in charge of executing the Buy-back Programme- that it has carried out the following transactions over its own shares between 15 October and 21 October, 2021 (both included):

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), 22 October 2021

ANNEX I

Detailed information on each of the transactions carried out within the context of the Buy-back Programme between 15 October and 21 October 2021 (both included)