Whitefort outlines 8.1% Arbutus Biopharma (ABUS) stake in amended 13D

Rhea-AI Filing Summary

Whitefort Capital and related entities report beneficial ownership of 15,794,261 Arbutus Biopharma common shares, or approximately 8.1% of the class, in this amended Schedule 13D. The stake is based on 195,478,068 shares outstanding as of March 18, 2026.

The shares were purchased by Whitefort Capital Master Fund using working capital, which may include margin loans, for an aggregate purchase price of about $41,839,734 including brokerage commissions. Multiple Whitefort entities and Messrs. David Salanic and Joseph Kaplan may be deemed beneficial owners and expressly disclaim ownership of securities they do not directly own.

The amendment updates the ownership calculations and adds an exhibit listing all transactions in Arbutus Biopharma shares by the reporting persons over the prior 60 days, noting that these trades occurred in the open market unless otherwise indicated.

Key Figures

Beneficial ownership: 15,794,261 shares Ownership percentage: 8.1% Aggregate purchase price: $41,839,734 +2 more

5 metrics

Beneficial ownership 15,794,261 shares Whitefort Master Fund and related persons’ stake in Arbutus Biopharma

Ownership percentage 8.1% Portion of Arbutus Biopharma common shares outstanding

Aggregate purchase price $41,839,734 Cost for 15,794,261 shares including brokerage commissions

Shares outstanding 195,478,068 shares Arbutus Biopharma common shares outstanding as of March 18, 2026

Event date April 10, 2026 Date of event requiring the amended Schedule 13D filing

Key Terms

beneficially owns, working capital, margin loans, dispositive power, +1 more

5 terms

beneficially owns financial

"As of the date hereof, Whitefort Master Fund beneficially owns 15,794,261 Shares"

Beneficially owns means a person or entity enjoys the economic benefits and control of a security even if the legal title or registration is held in another name. Think of it like having the keys and profits from a car that is registered to a friend: you use it, benefit from it, and make decisions about it even though the official paperwork lists someone else. For investors, this matters because it reveals who truly controls shares, affects voting power, potential conflicts of interest, and regulatory disclosure obligations.

working capital financial

"purchased by Whitefort Master Fund were purchased with working capital"

Working capital is the money a business has available to cover its daily expenses, like paying bills and buying supplies. It’s like the cash in your wallet that helps you handle everyday costs; having enough ensures the business can operate smoothly without running into money shortages.

margin loans financial

"which may, at any given time, include margin loans made by brokerage firms"

Margin loans are loans from a brokerage that let an investor borrow money using their existing stocks, bonds or cash as collateral to buy more securities. They matter because borrowing magnifies both gains and losses—like using a lever to move a heavier load—so small market moves can have outsized effects on your returns; investors also pay interest and risk a margin call, where the broker may force sales if collateral falls below required levels.

dispositive power financial

"Number of Shares Beneficially Owned by Each Reporting Person With: 9 | Sole Dispositive Power"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

Schedule 13D regulatory

"The filing of this shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d)"

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.

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

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Accepted by SEC EDGAR 04/13/2026 - 07:56 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)

Arbutus Biopharma Corp

(Name of Issuer)

Common Shares, without par value

(Title of Class of Securities)

03879J100

(CUSIP Number)

DAVID SALANIC
WHITEFORT CAPITAL MANAGEMENT, LP, 12 East 49th Street, 40th Floor
New York, NY, 10017
212-259-4370

JOSEPH KAPLAN
WHITEFORT CAPITAL MANAGEMENT, LP, 12 East 49th Street, 40th Floor
New York, NY, 10017
212-259-4370

RYAN NEBEL
OLSHAN FROME WOLOSKY LLP, 1325 Avenue of the Americas
New York, NY, 10019
212-451-2300

PATRICIA OLASKER
DAVIES WARD PHILLIPS & VINEBERG LLP, 155 Wellington Street West
Toronto, A6, M5V 3J7
416-863-0900

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

04/10/2026

(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): 03879J100

1

Name of reporting person

Whitefort Capital Master Fund, LP

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)

WC

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 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 03879J100

1

Name of reporting person

Whitefort Capital GP, LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 03879J100

1

Name of reporting person

Whitefort Capital Management, LP

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s): 03879J100

1

Name of reporting person

Whitefort Capital Management GP, LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 03879J100

1

Name of reporting person

David Salanic

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

FRANCE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

CUSIP Number(s): 03879J100

1

Name of reporting person

Joseph Kaplan

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 STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 15,794,261.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 15,794,261.00

11

Aggregate amount beneficially owned by each reporting person

15,794,261.00

12

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

13

Percent of class represented by amount in Row (11)

8.1 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Shares, without par value
(b)	Name of Issuer: Arbutus Biopharma Corp
(c)	Address of Issuer's Principal Executive Offices: 701 VETERANS CIRCLE, WARMINSTER, PENNSYLVANIA , 18974.
Item 3.	Source and Amount of Funds or Other Consideration
	Item 3 is hereby amended and restated to read as follows: The securities of the Issuer purchased by Whitefort Master Fund were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business). The aggregate purchase price of the 15,794,261 Shares owned directly by Whitefort Master Fund is approximately $41,839,734, including brokerage commissions.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5(a) is hereby amended and restated to read as follows: The aggregate percentage of Shares reported owned by each person named herein is based upon 195,478,068 Shares outstanding as of March 18, 2026, which is the total number of Shares outstanding as reported in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 23, 2026. As of the date hereof, Whitefort Master Fund beneficially owns 15,794,261 Shares, constituting approximately 8.1% of the Shares outstanding. Whitefort Master GP, as the general partner of Whitefort Master Fund, may be deemed to beneficially own the 15,794,261 Shares owned by Whitefort Master Fund, constituting approximately 8.1% of the Shares outstanding. Whitefort Management, as the investment manager of Whitefort Master Fund, may be deemed to beneficially own the 15,794,261 Shares owned by Whitefort Master Fund, constituting approximately 8.1% of the Shares outstanding. Whitefort GP, as the general partner of Whitefort Management, may be deemed to beneficially own the 15,794,261 Shares owned by Whitefort Master Fund, constituting approximately 8.1% of the Shares outstanding. Each of Messrs. Salanic and Kaplan, as a Co-Managing Partner of Whitefort Management and a Co-Managing Member of each of Whitefort Master GP and Whitefort GP, may be deemed to beneficially own the 15,794,261 Shares owned by Whitefort Master Fund, constituting approximately 8.1% of the Shares outstanding. The filing of this Schedule 13D shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any securities of the Issuer he or it does not directly own. Each of the Reporting Persons specifically disclaims beneficial ownership of the securities reported herein that he or it does not directly own.
(c)	Item 5(c) is hereby amended and restated to read as follows: The transactions in securities of the Issuer by the Reporting Persons during the past 60 days are set forth in Exhibit 1 and are incorporated herein by reference. All of such transactions were effected in the open market unless otherwise noted therein.
Item 7.	Material to be Filed as Exhibits.
	Item 7 is hereby amended to add the following exhibit: 1 - Transactions in Securities.

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.

Whitefort Capital Master Fund, LP

Signature:	/s/ David Salanic
Name/Title:	David Salanic, Co-Managing Member of Whitefort Capital GP, LLC, its General Partner
Date:	04/13/2026

Signature:	/s/ Joseph Kaplan
Name/Title:	Joseph Kaplan, Co-Managing Member of Whitefort Capital GP, LLC, its General Partner
Date:	04/13/2026

Whitefort Capital GP, LLC

Signature:	/s/ David Salanic
Name/Title:	David Salanic, Co-Managing Member
Date:	04/13/2026

Signature:	/s/ Joseph Kaplan
Name/Title:	Joseph Kaplan, Co-Managing Member
Date:	04/13/2026

Whitefort Capital Management, LP

Signature:	/s/ David Salanic
Name/Title:	David Salanic, Co-Managing Partner
Date:	04/13/2026

Signature:	/s/ Joseph Kaplan
Name/Title:	Joseph Kaplan, Co-Managing Partner
Date:	04/13/2026

Whitefort Capital Management GP, LLC

Signature:	/s/ David Salanic
Name/Title:	David Salanic, Co-Managing Member
Date:	04/13/2026

Signature:	/s/ Joseph Kaplan
Name/Title:	Joseph Kaplan, Co-Managing Member
Date:	04/13/2026

David Salanic

Signature:	/s/ David Salanic
Name/Title:	David Salanic
Date:	04/13/2026

Joseph Kaplan

Signature:	/s/ Joseph Kaplan
Name/Title:	Joseph Kaplan
Date:	04/13/2026