Astaris lifts KNOT Offshore Partners (NYSE: KNOP) stake to 8% amid cash offer

Rhea-AI Filing Summary

Astaris Capital Management and affiliates filed Amendment No. 3 to a Schedule 13D disclosing beneficial ownership of 2,695,018 common units of KNOT Offshore Partners LP, representing 8.0% of the outstanding units. The units are held by advisory clients of Astaris Capital Management LLP, with Astaris and Martin Beck sharing voting and dispositive power.

The filing notes this reflects an increase of over 1% in beneficial ownership. It also references a non‑binding offer delivered on October 31, 2025 by Knutsen NYK Offshore Tankers AS to acquire all KNOT Offshore Partners common units not already owned by it for cash. The reporting persons state their holdings are for investment purposes and that they may buy more, sell, or engage with the board and other shareholders regarding the offer and broader strategic and governance matters.

Insights

Equity ownership and activism analyst

Astaris lifts KNOP stake to 8%, signaling active engagement potential.

The filing shows Astaris Capital Management and related entities now beneficially own 2,695,018 KNOT Offshore Partners common units, or 8.0% of the 33,660,342 units outstanding as of December 31, 2025. All units are held in advisory client accounts, with shared voting and disposition power.

The amendment is triggered by an increase of over 1% in beneficial ownership, indicating incremental accumulation rather than a new position. The filing cites a non‑binding offer from Knutsen NYK Offshore Tankers AS dated October 31, 2025 to buy all remaining common units for cash, and notes that Astaris may discuss this proposal and other strategic or governance topics with the board and other shareholders.

Overall, this looks like an engaged institutional holder building an 8% stake around a potential take‑private transaction. The actual impact will depend on future negotiations and any subsequent transaction terms the issuer may disclose in later filings.

Key Figures

Beneficial ownership: 2,695,018 common units Ownership percentage: 8.0% of common units Units outstanding: 33,660,342 common units +3 more

6 metrics

Beneficial ownership 2,695,018 common units Units beneficially owned by reporting persons

Ownership percentage 8.0% of common units Based on units outstanding as of December 31, 2025

Units outstanding 33,660,342 common units Outstanding as of December 31, 2025 per Form 20-F

Date of triggering event 06/18/2026 Date of event requiring Amendment No. 3

Amendment number Amendment No. 3 Schedule 13D amendment filed by reporting persons

Non-binding offer date October 31, 2025 Date of offer letter from Knutsen NYK Offshore Tankers AS

Key Terms

beneficial owner, Schedule 13D, non-binding offer, Common Units Representing Limited Partner Interests, +1 more

5 terms

beneficial owner financial

"may be deemed to be the beneficial owner of 2,695,018 Common Units"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

Schedule 13D regulatory

"filed a statement on Schedule 13G to report the acquisition"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

non-binding offer financial

"delivered a non-binding offer (the "Offer Letter") to the board"

Common Units Representing Limited Partner Interests financial

"Title of Class of Securities: Common Units Representing Limited Partner Interests"

investment adviser financial

"principal business of Astaris Capital Management LLP is serving as an investment adviser"

An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.

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Available on EDGAR 06/23/2026 - 12:26 PM Accepted by SEC EDGAR 06/23/2026 - 12:25 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)

KNOT Offshore Partners LP

(Name of Issuer)

Common Units Representing Limited Partner Interests

(Title of Class of Securities)

Y48125101

(CUSIP Number)

Martin Beck
Astaris Capital Management LLP, 3 Tilney Street
London, X0, W1K 1BQ
44 20 7590 5401

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

06/18/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): Y48125101

1

Name of reporting person

Astaris Capital Management LLP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED KINGDOM

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,695,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,695,018.00

11

Aggregate amount beneficially owned by each reporting person

2,695,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

8.0 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s): Y48125101

1

Name of reporting person

Astaris Capital Management (UK) Limited

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED KINGDOM

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,695,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,695,018.00

11

Aggregate amount beneficially owned by each reporting person

2,695,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

8.0 %

14

Type of Reporting Person (See Instructions)

CO, HC

SCHEDULE 13D

CUSIP Number(s): Y48125101

1

Name of reporting person

Astaris Capital Management (Cayman) Limited

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,695,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,695,018.00

11

Aggregate amount beneficially owned by each reporting person

2,695,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

8.0 %

14

Type of Reporting Person (See Instructions)

CO, HC

SCHEDULE 13D

CUSIP Number(s): Y48125101

1

Name of reporting person

Martin Beck

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED KINGDOM

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 2,695,018.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,695,018.00

11

Aggregate amount beneficially owned by each reporting person

2,695,018.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

8.0 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Units Representing Limited Partner Interests
(b)	Name of Issuer: KNOT Offshore Partners LP
(c)	Address of Issuer's Principal Executive Offices: 2 QUEEN'S CROSS, ABERDEEN, UNITED KINGDOM , AB15 4YB.
Item 1 Comment: The name of the issuer is KNOT Offshore Partners LP, a Marshall Islands limited partnership (the "Issuer"). The address of the Issuer's principal executive offices is 2 Queens Cross, Aberdeen, AB15 4YB, United Kingdom. This Schedule 13D Amendment No. 3 relates to the Issuer's Common Units Representing Limited Partner Interests (the "Common Units").
Item 2.	Identity and Background
(a)	(a), (f) This Schedule 13D is being filed by Astaris Capital Management LLP, a United Kingdom limited liability partnership, Astaris Capital Management (UK) Limited, a United Kingdom private limited company, Astaris Capital Management (Cayman) Limited, a Cayman Islands exempted company and Martin Beck, a citizen of the United Kingdom (each a "Reporting Person" and collectively, the "Reporting Persons").
(b)	The principal business address for each of Astaris Capital Management LLP, Astaris Capital Management (UK) Limited and Martin Beck is 3 Tilney Street, London W1K 1BQ, United Kingdom. The principal business address for Astaris Capital Management (Cayman) Limited is P.O. Box 309, Ugland House, Grand Cayman KY1-1104, Cayman Islands.
(c)	The principal business of Astaris Capital Management LLP is serving as an investment adviser to its clients. Astaris Capital Management (UK) Limited, Astaris Capital Management (Cayman) Limited and Martin Beck may be considered control persons of Astaris Capital Management LLP.
(d)	(d), (e) During the last five years, none of the Reporting Persons has been (a) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (b) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws. The Reporting Persons disclaim membership in a group.
Item 3.	Source and Amount of Funds or Other Consideration
	The funds used for the acquisition of the Common Units beneficially owned by the Reporting Persons came from the working capital of private funds and managed account clients advised by Astaris Capital Management LLP. No borrowed funds were used to purchase the Common Units of the Issuer other than any borrowed funds used for working capital purposes in the ordinary course of business.
Item 4.	Purpose of Transaction
	This Schedule 13D Amendment No. 3 is being filed to report an increase of over 1% in beneficial ownership of the Common Units of the Issuer. The Reporting Persons acquired the securities reported herein for investment purposes and intend to review their investments in the Issuer on a continuing basis. Subject to various factors, including but not limited to the Issuer's financial position and strategic direction, price levels of the Common Units, conditions in the securities markets, various laws and regulations applicable to the Issuer and companies in its industry and the Reporting Persons' ownership in the Issuer, and general economic and industry conditions, the Reporting Persons may in the future take actions with respect to their investment in the Issuer as they deem appropriate, including changing their current intentions, with respect to any or all matters required to be disclosed in this Schedule 13D. The Reporting Persons may, from time to time, acquire, or cause affiliates to acquire, additional Common Units or other securities of the Issuer (including any combination or derivative thereof), dispose, or cause affiliates to dispose, of some or all of their Common Units or other securities of the Issuer or continue to hold, or cause affiliates to hold, Common Units or other securities of the Issuer (or any combination or derivative thereof). In addition, on October 31, 2025, Knutsen NYK Offshore Tankers AS, a Norway limited company ("KNOT"), delivered a non-binding offer (the "Offer Letter") to the board of directors of the Issuer (the "Board"), to acquire all of the issued and outstanding Common Units that are not already beneficially owned by KNOT in exchange for cash. The Reporting Persons have discussed and/or may discuss from time to time, with management, the Board and any of its committees, other shareholders of the Issuer and/or other third parties about the Offer Letter or any subsequent proposed or negotiated transaction, and the proposed terms contained therein, and the Issuer's business, operations, strategy (including with respect to capital allocation policies and procedures), plans and prospects and governance matters generally and in relation to the Reporting Persons' investment in the Issuer and requesting information from the Issuer related thereto. Except as described in this Schedule 13D, none of the Reporting Persons has any present plans or proposals that relate to or would result in any of the actions described in Item 4 of this Schedule 13D, although, the Reporting Persons, at any time and from time to time, may review, reconsider and change their position and/or purpose and/or develop such plans and may from time to time consider pursuing or proposing such matters with advisors, the Issuer or other persons.
Item 5.	Interest in Securities of the Issuer
(a)	As of the date hereof, each of the Reporting Persons may be deemed to be the beneficial owner of 2,695,018 Common Units, constituting 8.0% of the Common Units of the Issuer, based on 33,660,342 Common Units outstanding as of December 31, 2025, as reported in the Issuer's Form 20-F filed with the Securities and Exchange Commission on April 17, 2026.
(b)	Each of the Reporting Persons has the sole power to vote or direct the vote of, and the sole power to dispose or direct the disposition of 0 Common Units. Each of the Reporting Persons has the shared power to vote or direct the vote of, and the shared power to dispose or direct the disposition of 2,695,018 Common Units.
(c)	Please see Exhibit B for a list of transactions effected in the past sixty days in the securities of the Issuer by the Reporting Persons.
(d)	All of the securities reported in this Schedule 13D Amendment No. 3 are directly owned by advisory clients of Astaris Capital Management LLP. None of those advisory clients may be deemed to beneficially own more than 5% of the Common Units.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	The Reporting Persons' response to Item 4 is incorporated by reference into this Item 6.
Item 7.	Material to be Filed as Exhibits.
	Exhibit A: Joint Filing Agreement

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Astaris Capital Management LLP

Signature:	/s/ Martin Beck
Name/Title:	Martin Beck, Partner & Designated Member
Date:	06/23/2026

Astaris Capital Management (UK) Limited

Signature:	/s/ Martin Beck
Name/Title:	Martin Beck, Director
Date:	06/23/2026

Astaris Capital Management (Cayman) Limited

Signature:	/s/ Martin Beck
Name/Title:	Martin Beck, Director
Date:	06/23/2026

Martin Beck

Signature:	/s/ Martin Beck
Name/Title:	Martin Beck
Date:	06/23/2026

Comments accompanying signature:

* Each Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein, and this report shall not be deemed an admission that any such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the U.S. Securities Exchange Act of 1934, as amended, or for any other purpose.

FAQ

How much of KNOT Offshore Partners LP (KNOP) does Astaris now own?

Astaris Capital Management and related reporting persons beneficially own 2,695,018 common units of KNOT Offshore Partners LP, equal to 8.0% of the issuer’s common units, based on 33,660,342 units outstanding as of December 31, 2025.

What triggered this Amendment No. 3 to the KNOP Schedule 13D?

The amendment was filed to report an increase of over 1% in Astaris’s beneficial ownership of KNOT Offshore Partners’ common units. It updates prior disclosures to reflect the higher 8.0% stake and current intentions regarding the investment.

Who actually holds the KNOP units reported by Astaris in this filing?

All reported KNOT Offshore Partners units are directly owned by advisory clients of Astaris Capital Management LLP. Astaris and Martin Beck share voting and dispositive power, and no single advisory client beneficially owns more than 5% of the common units.

What are Astaris’s stated intentions for its KNOP investment?

Astaris reports holding KNOT Offshore Partners units for investment purposes and may buy more, sell some or all, or continue holding. It may also engage with management, the board, other shareholders, and third parties about strategy, capital allocation, governance, and any potential transactions.

What non-binding offer involving KNOT Offshore Partners is mentioned in this filing?

The filing notes an October 31, 2025 non‑binding offer from Knutsen NYK Offshore Tankers AS to acquire all KNOT Offshore Partners common units it does not already own for cash. Astaris may discuss this offer and any related proposals with the board and other stakeholders.

Does any single Astaris client exceed 5% ownership of KNOP units?

No. The statement specifies that all securities are owned by advisory clients of Astaris Capital Management LLP and that none of those advisory clients may be deemed to beneficially own more than 5% of KNOT Offshore Partners’ common units.