6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13A-16 OR 15D-16 OF THE

SECURITIES EXCHANGE ACT OF 1934

For the month of May 2026

Commission File Number: 001-41889

CADELER A/S

(Translation of registrant's name into English)

Kalvebod Brygge 43

DK-1560 Copenhagen V, Denmark

(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 x Form 40-F o

Stock exchange announcement

CADELER A/S: COMPLETION OF SHARE BUY-BACK PROGRAMME AND DISCLOSURE OF REPURCHASE TRANSACTIONS MADE UNDER THE SHARE BUY-BACK PROGRAMME

Copenhagen, 28 May 2026: Cadeler A/S (OSE: CADLR, NYSE: CDLR) (“Cadeler”) today confirms that it has completed the share buy-back programme it announced on 27 May 2026 in advance of the programme’s anticipated termination date of 5 June 2026, as the maximum number of shares to be repurchased under the programme was reached earlier than that date. The share buy-back programme has therefore been terminated early.

On 27 May 2026, Cadeler repurchased 105,275 of its own shares at an average price per share of NOK 49.92, corresponding to an aggregate purchase price before commission of NOK 6,596,058, or approximately EUR 0.6 million.

On 27 May 2026, Cadeler initiated a share buy-back programme of up to NOK 7.6 million (approx. EUR 0.7 million) to enable Cadeler to meet its obligations to its employees arising from certain of Cadeler’s share-based incentive programmes (the “Programme”) in accordance with Article 5 of Regulation (EU) no. 596/2014 of the European Parliament and of the Council of 16 April 2014, as amended (the “Market Abuse Regulation”), and the Commissions Delegated Regulation (EU) 2016/1052 of 8 March 2016 (together with the Market Abuse Regulation, the “Safe Harbour Rules”). Further details on the terms of the Programme can be found in Cadeler’s stock exchange announcement dated 27 May 2026.

The following transactions were made under the Programme on 27 May 2026:

1 EUR figures presented based on the prevailing NOK/EUR exchange rate on 27 May 2026.

Details of each transaction made under the Programme are attached as an appendix to this stock exchange announcement.

Following the conclusion of the Programme Cadeler holds a total of 169,267 shares in treasury, each with a nominal value of DKK 1.00 and corresponding in the aggregate to less than 0.1% of Cadeler’s total share capital and voting rights of Cadeler.

For further information, please contact:

Mikkel Gleerup, CEO

+45 3246 3102

[email protected]

Alexander Simmonds, EVP & CLO

+44 7376 174172

[email protected]

About Cadeler A/S:

Cadeler A/S (Cadeler) is a pure-play offshore wind installation partner and a global leader in offshore wind turbine transport and installation. The company owns and operates the industry’s largest fleet of jack-up offshore wind installation vessels and is expanding its capabilities into full-scope foundation transport and installation, as well as operations & maintenance. With its modern fleet and depth of expertise across onshore and offshore operations, Cadeler supports the safe, efficient and reliable delivery of offshore wind projects worldwide. Cadeler is listed on the New York Stock Exchange (ticker: CDLR) and the Oslo Stock Exchange (ticker: CADLR).

For more information, please visit www.cadeler.com.

Appendix: Disclosure of transaction data under the share repurchase programme for Cadeler A/S on 27 May 2026

This document discloses the transactions made under the share repurchase programme for Cadeler A/S on 27 May 2026 in a detailed and aggregated form in accordance with Commission Delegated Regulation (EU) 2016/1052 of 8 March 2016 supplementing Regulation (EU) No. 596/2014 of the European Parliament and of the Council of 16 April 2014, as amended, with regards to regulatory technical standards for the conditions applicable to buy-back programmes and stabilisation measures.

1 EUR figures presented based on the prevailing NOK/EUR exchange rate on 27 May 2026.

SIGNATURES

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.

Date: May 28, 2026                    CADELER A/S

(Registrant)

By: /s/ Mikkel Gleerup         Name:     Mikkel Gleerup Title:    Chief Executive Officer