What did Banco Santander (SAN) announce regarding its share buyback in this 6-K?

Banco Santander announced progress on its share Buyback Programme, stating it has invested €558,894,930 up to September 16, 2026, equal to about 30.6% of the programme’s maximum investment, and has repurchased roughly 18.2% of its outstanding shares as of 2021.

Banco Santander buyback hits €558.9M, 18% 2021 shares

Q: What proportion of Banco Santander’s buyback capacity has been used so far?

Banco Santander reports that the €558,894,930 invested in the Buyback Programme up to September 16, 2026 represents approximately 30.6% of the programme’s maximum investment amount approved by the Board of Directors.

Banco Santander details progress on its share Buyback Programme, having invested about 30.6% of its maximum amount and repurchased roughly 18.2% of shares outstanding as of 2021.

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

6-K

Rhea-AI Filing Summary

Banco Santander, S.A. (SAN) reports further progress on its Board-approved share Buyback Programme, disclosing purchases of its own shares between September 10 and 16, 2026. The cash amount invested in the programme to September 16, 2026 totals €558.9 million, which is approximately 30.6% of the Buyback Programme’s maximum investment amount. As a result of these repurchases, the bank states it has bought back approximately 18.2% of its outstanding shares as of 2021. During the September 10–16 period specifically, the bank repurchased 7,100,000 shares across several European trading venues at weighted average prices around €12.6–€12.8 per share.

Positive

Banco Santander has invested €558.9 million in its Buyback Programme, repurchasing approximately 18.2% of its outstanding shares as of 2021, signalling a substantial capital return to shareholders.

Negative

None.

Key Figures

Buyback cash amount to date: €558,894,930 Buyback maximum investment used: 30.6% Shares repurchased vs 2021 outstanding: 18.2% +3 more

6 metrics

Buyback cash amount to date €558,894,930 Cash amount of shares purchased under the Buyback Programme up to September 16, 2026

Buyback maximum investment used 30.6% Percentage of the Buyback Programme’s maximum investment amount used by September 16, 2026

Shares repurchased vs 2021 outstanding 18.2% Approximate proportion of outstanding shares as of 2021 repurchased through the Buyback Programme

Shares repurchased in period 7,100,000 shares Total shares repurchased between September 10 and 16, 2026

Weighted average price on XMAD (September 10, 2026) €12.6399 per share Banco Santander share purchases on XMAD on September 10, 2026

Weighted average price on XMAD (September 15, 2026) €12.6556 per share Banco Santander share purchases on XMAD on September 15, 2026

Key Terms

Buyback Programme, inside information, Market Abuse, Commission Delegated Regulation (EU) 2016/1052

4 terms

Buyback Programme financial

"relating to the buyback programme of own shares (the “Buyback Programme”)"

inside information regulatory

"Reference is made to our notice of inside information of 10 August 2026"

Information not available to the public that, if known, would likely cause a company’s stock or bonds to rise or fall—for example, undisclosed earnings, deals, product results, or management plans. It matters because trading on that information gives an unfair advantage, can distort market prices, and is typically illegal or subject to strict rules, so investors watch for proper disclosure and compliance to protect fair, transparent markets.

Market Abuse regulatory

"Pursuant to article 5 of Regulation (EU) no. 596/2014 on Market Abuse"

Market abuse is illegal or unethical behavior that distorts the price or fairness of buying and selling financial assets, such as using secret information to trade, spreading false or misleading news, or creating fake buying and selling to give a false impression of demand. It matters to investors because it can cause unfair losses, unreliable prices and legal or reputational fallout; like cheating in a game or tampering with a scale, it destroys confidence that markets reflect true value.

Commission Delegated Regulation (EU) 2016/1052 regulatory

"and articles 2.2 and 2.3 of Commission Delegated Regulation (EU) 2016/1052"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many Banco Santander (SAN) shares were repurchased between September 10 and 16, 2026?

Between September 10 and 16, 2026, Banco Santander repurchased a total of 7,100,000 shares under its Buyback Programme, executed across several trading venues including XMAD, CEUX, TQEX and AQEU at weighted average prices around €12.6–€12.8 per share.

What proportion of Banco Santander’s buyback capacity has been used so far?

Banco Santander reports that the €558,894,930 invested in the Buyback Programme up to September 16, 2026 represents approximately 30.6% of the programme’s maximum investment amount approved by the Board of Directors.

What portion of Banco Santander (SAN) shares has been repurchased through the Buyback Programme?

Banco Santander states that, with the reported purchases, it has repurchased approximately 18.2% of its outstanding shares as of 2021 through the Buyback Programme, indicating a significant reduction in the share count relative to that baseline.

On which markets did Banco Santander (SAN) execute the September 10–16, 2026 buyback trades?

During September 10–16, 2026, Banco Santander executed its buyback trades in its ordinary shares (ISIN ES0113900J37) on several venues: XMAD, CEUX, TQEX and AQEU, with each transaction’s details listed by date, venue, shares, and weighted average price.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/17/2026 - 06:04 AM Accepted by SEC EDGAR 09/17/2026 - 06:04 AM

FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of September, 2026

Commission File Number: 001-12518

Banco Santander, S.A.

(Exact name of registrant as specified in its charter)

Ciudad Grupo Santander

28660 Boadilla del Monte (Madrid) Spain

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F

Form 40-F

Banco Santander, S.A.

TABLE OF CONTENTS

Item

1	Report of Other Relevant Information dated September 17, 2026

Item 1

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 10 August 2026 (official registry number 3336) (the “Buyback Commencement Communication”), relating to the buyback programme of own shares (the “Buyback 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 10 and 16 September (both inclusive).

The cash amount of the shares purchased to 16 September 2026 as a result of the execution of the Buyback Programme amounts to 558,894,930 Euros, which represents approximately 30.6% of the maximum investment amount of the Buyback Programme. The programme was announced together with its other characteristics through the Buyback Commencement Communication. With these purchases, the Bank has repurchased approximately 18.2% of its outstanding shares as of 2021.

Date	Security	Transaction	Trading venue	Number of shares	Weighted average price (€)
10/09/2026	SAN	Purchase	XMAD	1,200,000	12.6399
10/09/2026	SAN	Purchase	CEUX	516,593	12.6483
10/09/2026	SAN	Purchase	TQEX	128,707	12.6582
10/09/2026	SAN	Purchase	AQEU	254,700	12.6577
11/09/2026	SAN	Purchase	XMAD	200,000	12.8061
14/09/2026	SAN	Purchase	XMAD	1,000,000	12.6782
14/09/2026	SAN	Purchase	CEUX	144,528	12.6865
14/09/2026	SAN	Purchase	TQEX	22,352	12.6966
14/09/2026	SAN	Purchase	AQEU	33,120	12.6677
15/09/2026	SAN	Purchase	XMAD	2,060,434	12.6556
15/09/2026	SAN	Purchase	CEUX	77,688	12.5967
15/09/2026	SAN	Purchase	TQEX	34,938	12.5972
15/09/2026	SAN	Purchase	AQEU	26,940	12.5911
16/09/2026	SAN	Purchase	XMAD	1,189,553	12.6782
16/09/2026	SAN	Purchase	CEUX	104,367	12.6737
16/09/2026	SAN	Purchase	TQEX	67,446	12.6621
16/09/2026	SAN	Purchase	AQEU	38,634	12.6643
			TOTAL	7,100,000

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 September 2026

ANNEX I

Detailed information on each of the transactions carried out within the context of the Buy-back Programme between 10/09/2026 and 16/09/2026 (both inclusive)

(https://www.santander.com/content/dam/santander-com/es/documentos/cumplimiento/do-anexo-i-10-a-16-septiembre-2026-es.pdf)

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

		Banco Santander, S.A.


Date:	September 17, 2026	By:	/s/ Pedro de Mingo Kaminouchi
			Name:	Pedro de Mingo Kaminouchi
			Title:	Head of Corporate Compliance

Source: View Original Filing on SEC EDGAR