Korsana Biosciences has 6.1% passive holder

An institutional Wellington-affiliated fund reports a 6.10% beneficial stake in Korsana Biosciences (CYCN), with shared voting and dispositive power over 2,775,788 common shares.

Rhea-AI Filing Summary

Korsana Biosciences, Inc. (CYCN) is reported to have a significant shareholder, Wellington Biomedical Innovation Master Investors (Cayman) II, L.P., which has filed as a passive holder on a Schedule 13G. The fund reports beneficial ownership of 2,775,788 shares of common stock, representing 6.10% of the class.

The filing states the holder has shared power to vote and dispose of all 2,775,788 shares, with no sole voting or dispositive power. This positions the Wellington-affiliated fund as a notable institutional investor in Korsana Biosciences without indicating any change of control intent.

Key Figures

Beneficially owned shares: 2,775,788 shares Percent of class owned: 6.10% Shared voting power: 2,775,788 shares +2 more

5 metrics

Beneficially owned shares 2,775,788 shares Common stock of Korsana Biosciences, Inc. reported by the Wellington fund

Percent of class owned 6.10% Percentage of Korsana Biosciences common stock class beneficially owned

Shared voting power 2,775,788 shares Shares over which the fund has shared power to vote or direct the vote

Sole voting power 0 shares Shares over which the fund has sole power to vote

Shared dispositive power 2,775,788 shares Shares over which the fund has shared power to dispose or direct disposition

Key Terms

Schedule 13G, beneficial ownership, shared voting power, shared dispositive power, +1 more

5 terms

Schedule 13G regulatory

"which has filed as a passive holder on a Schedule 13G"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

beneficial ownership financial

"Amount beneficially owned: 2,775,788"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared voting power financial

"Shared Voting Power 2,775,788.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 2,775,788.00"

percent of class financial

"Percent of class: 6.10 %"

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

FAQ

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

What stake in CYCN does Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. report?

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. reports beneficial ownership of 2,775,788 shares of Korsana Biosciences, Inc. common stock, representing 6.10% of the class, according to the Schedule 13G filing.

Does the Wellington fund have sole or shared voting power over CYCN shares?

The filing states the fund has 0 shares with sole voting power and 2,775,788 shares with shared voting power. All reported Korsana Biosciences shares are held with shared voting authority, not sole control.

What dispositive power does the Wellington fund report over CYCN stock?

The fund reports no sole dispositive power and shared dispositive power over 2,775,788 shares of Korsana Biosciences common stock, meaning decisions to sell or otherwise dispose of these shares are shared.

Who is the reporting person on this Schedule 13G for CYCN?

The reporting person is Wellington Biomedical Innovation Master Investors (Cayman) II, L.P., with its principal business office listed as c/o Wellington Management Company LLP, 280 Congress Street, Boston, Massachusetts.

What is the security class and CUSIP for Korsana Biosciences in this filing?

The security covered is Korsana Biosciences, Inc. common stock, and the filing lists the CUSIP number 23255M303 for this class of securities.

Who signed the Schedule 13G related to CYCN on behalf of the Wellington fund?

The Schedule 13G is signed by Ihsan Speede as an Authorized Person, with a comment that Wellington Alternative Investments LLC is the general partner. The signature is dated September 16, 2026.

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

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Available on EDGAR 09/16/2026 - 07:56 AM Accepted by SEC EDGAR 09/16/2026 - 07:55 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Korsana Biosciences, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

23255M303

(CUSIP Number)

09/09/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 23255M303

1

Names of Reporting Persons

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,775,788.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,775,788.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,775,788.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.1 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Korsana Biosciences, Inc.
(b)	Address of issuer's principal executive offices: 221 Crescent St, Building 23, Suite 105, Waltham MA
Item 2.
(a)	Name of person filing: Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.
(b)	Address or principal business office or, if none, residence: c/o Wellington Management Company LLP, 280 Congress Street, Boston MA 02210
(c)	Citizenship: Cayman Islands
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 23255M303
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2,775,788
(b)	Percent of class: 6.10 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 2,775,788
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2,775,788
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

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.

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.

Signature:	Ihsan Speede
Name/Title:	Authorized Person
Date:	09/16/2026

Comments accompanying signature: Wellington Alternative Investments LLC; Its General Partner Signature: Ihsan Speede Name/Title: Authorized Person Date: 09/16/2026