Korsana Biosciences, Inc.: 5%+ holders

As of November 8, 2026, 8 holders' latest Schedule 13D or 13G filings report owning 5% or more of Korsana Biosciences, Inc. The largest reported stake is Fairmount Funds Management LLC's, at 19.99%. 12 filings are on record since August 14, 2025 (Schedule 13D, September 11, 2026).

J. Wood Capital Advisors LLC also filed stake reports on 1 other company ↓

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Key facts

• Filed 2026-10-15 · Holder: J. Wood Capital Advisors LLC · Percent: 0.1% · SCHEDULE 13G/A
• Filing 2026-10-07 · Reporting person: Fmr LLC · Sole voting: 3,144,797 · Shared voting: 0 · Sole dispositive: 3,144,797 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-10-07
• Filed 2026-09-18 · Holder: General Atlantic, L.P. · Percent: 6.8% · SCHEDULE 13G
• Filed 2026-09-16 · Holder: Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. · Percent: 6.1% · SCHEDULE 13G
• Filing 2026-09-15 · Reporting person: Venrock Healthcare Capital Partners III, L.P. · Sole voting: 0 · Shared voting: 4,552,277 · Sole dispositive: 0 · Shared dispositive: 4,552,277 · SCHEDULE 13D, 2026-09-15

Korsana Biosciences, Inc. has 12 Schedule 13D or 13G filings on record since 2025-08-14. 8 holders' latest filing reports 5% or more of common stock, no par value. Each figure below is the holder's own, as filed, with the filing linked.

Holders

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More on Korsana Biosciences, Inc. and the records around it.

Korsana Biosciences, Inc. elsewhere on the record

• Leadership changes Sep 2026
• Who owns it

Companies that share a holder

• J. Wood Capital Advisors LLC also filed stake reports on 1 other company: Karyopharm Therapeutics Inc. (Nov 2025)
• Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. also filed stake reports on 2 other companies: ProMIS Neurosciences, Inc. (Aug 2026), MBX Biosciences (Nov 2025)
• GENERAL ATLANTIC, L.P. also filed stake reports on 10 other companies: dLocal Ltd (Aug 2026), Pharvaris N.V. (Aug 2026), Liftoff Mobile, Inc. (Jun 2026)

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Voting and dispositive power, as filed

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The latest filing identifies Korsana Biosciences, Inc. by CUSIP 23255M303 and gives its principal executive office as 203 Crescent Street, Bldgs. #3/3A/4, Suite 503, Waltham, MA 02453 (SCHEDULE 13G/A, 2026-10-15).

What the percentages are based on

Each of the Reporting Persons may be deemed to be the beneficial owner of approximately 7.33% of the Shares, based on 4,330,314 Shares of common stock outstanding as of May 10, 2026 as reported in the Issuer's 10-Q filed with the Securities and Exchange Commission on May 12, 2026.Balyasny Asset Management L.P., SCHEDULE 13G, 2026-08-14

The percentages used herein are calculated based upon an aggregate of 47,376,314 shares of common stock, consisting of (i) 45,541,425 shares of common stock reported by the Company to be issued and outstanding as of September 8, 2026 reflected in the Company's Current Report on Form 8-K filed with the U.S.General Atlantic, L.P., SCHEDULE 13G, 2026-09-18

Source of funds (Item 3)

In aggregate, the Reporting Persons have voting and dispositive power over 9,103,729 shares of Common Stock, which is comprised of (a) 6,911,174 shares of Common Stock directly held by Fund II and 2,192,555 shares of Common Stock directly held by Co-Invest, and exclude (b) 2,074,000 shares of Common Stock issuable upon conversion of 2,074 shares of Series B Preferred Stock directly held by Fund II and 66,436 shares of Common Stock issuable upon exercise of Pre-Funded Warrants directly held by Fund II.Fairmount Funds Management LLC, SCHEDULE 13D, 2026-09-11

On September 8, 2026, the Issuer completed the transactions contemplated by the Agreement and Plan of Merger, dated April 1, 2026, by and among the Issuer (which was formerly known as Cyclerion Therapeutics, Inc.), Cariboos Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of Cyclerion, Cariboos Merger Sub II, LLC, a Delaware limited liability company and wholly owned subsidiary of the Issuer, and Korsana Biosciences, Inc., a private Delaware corporation ("Old Korsana" and such transaction, the "Merger").Venrock Healthcare Capital Partners III, L.P., SCHEDULE 13D, 2026-09-15

Purpose of Transaction (Item 4)

Fairmount Funds Management LLC

The Reporting Persons own 19.99% of the Company in the aggregate, based upon the Company's aggregate outstanding shares as of September 8, 2026. The Reporting Persons' securities include (a) 2,691 shares of Common Stock issuable upon the exercise of options held directly by Mr. Kiselak that are currently exercisable or will be exercisable within 60 days of the date of this filing, (b) 6,911,174 shares of Common Stock directly held by Fund II and (c) 2,192,555 shares of Common Stock directly held by Co-Invest, and exclude (i) 2,074,000 shares of Common Stock issuable upon conversion of 2,074 shares of Series B Preferred Stock directly held by Fund II and (ii) 66,436 shares of Common Stock issuable upon exercise of Pre-Funded Warrants directly held by Fund II. The exercise of the Pre-Funded Warrants is subject to a beneficial ownership limitation of 19.99% of the outstanding shares of Common Stock and the conversion of the Series B Preferred Stock is subject to a beneficial ownership limitation of 19.99% of the outstanding shares of Common Stock. The securities exclude shares of Common Stock issuable upon exercise of Pre-Funded Warrants and conversion of Series B Preferred Stock in excess of such beneficial ownership limitations. At such time as Fairmount and its affiliates beneficially own 9.0% or less of the outstanding shares of Common Stock, the beneficial ownership limitation with respect to the Series B Preferred Stock will automatically reduce to 9.99%. Mr. Kiselak …The first part of Item 4 of the SCHEDULE 13D filed 2026-09-11; the filing has the rest

Venrock Healthcare Capital Partners III, L.P.

The Reporting Persons purchased the aforementioned securities for investment purposes with the aim of increasing the value of their investments and the Issuer. Subject to applicable legal requirements, one or more of the Reporting Persons may purchase additional securities of the Issuer from time to time in open market or private transactions, depending on its evaluation of the Issuer's business, prospects and financial condition, the market for the Issuer's securities, other developments concerning the Issuer, the reaction of the Issuer to the Reporting Persons' ownership of the Issuer's securities, other opportunities available to the Reporting Persons, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above, the Reporting Persons may dispose of all or a portion of their securities of the Issuer at any time (including by means of programs adopted pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934 (the "Act")). Each of the Reporting Persons reserves the right to increase or decrease its holdings on such terms and at such times as each may decide. Except as set forth in this Item 4 and Item 6 below, none of the Reporting Persons has a present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D of the Act. However, each of the Reporting Persons reserves the right to propose or participate in future transactions …The first part of Item 4 of the SCHEDULE 13D filed 2026-09-15; the filing has the rest

Timeline

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Questions about who owns Korsana Biosciences, Inc.

Who owns Korsana Biosciences, Inc.?

On this page, 8 holders' latest ownership filings report 5% or more of Korsana Biosciences, Inc.: Fairmount Funds Management LLC (19.99%, Schedule 13D, filed 2026-09-11), Peter M. Hecht (19.4%, Schedule 13D/A, filed 2026-07-20), Venrock Healthcare Capital Partners III, L.P. (9.9%, Schedule 13D, filed 2026-09-15), Balyasny Asset Management L.P. (7.33%, Schedule 13G, filed 2026-08-14) and ADAR1 Capital Management, LLC (7%, Schedule 13G, filed 2026-08-14); 3 more are listed above.

Who are the largest shareholders of Korsana Biosciences, Inc.?

By the share each holder's latest filing reports, the largest holders of Korsana Biosciences, Inc. on this page are Fairmount Funds Management LLC (19.99%), Peter M. Hecht (19.4%) and Venrock Healthcare Capital Partners III, L.P. (9.9%).

When did Fairmount Funds Management LLC buy into Korsana Biosciences, Inc.?

The filings give report dates, not purchase dates. The earliest filing from Fairmount Funds Management LLC on this page is the Schedule 13D, filed 2026-09-11, reporting 19.99%.

Is this an audit or a full list?

Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 12 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.

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Where this comes from

Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.

Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.

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