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Keros Therapeutics ownership disclosure: Nantahala Capital Management, LLC and its managing members, Wilmot B. Harkey and Daniel Mack, report beneficial ownership of 1,360,419 shares of Common Stock, representing 6.90% of shares outstanding as of March 31, 2026. The filing states shared voting and dispositive power over these shares.
Insights
Large passive holding disclosed: 1,360,419 shares (6.90%).
The filing shows an investment adviser, Nantahala Capital Management, controls these shares across funds and accounts and that two managing members are reported as control persons. Ownership is reported as shared voting and dispositive power rather than sole control.
Implications depend on whether Nantahala changes its stake; subsequent filings would show any acquisitions or dispositions.
Reporting clarifies attribution and control-person status.
The schedule classifies Messrs. Harkey and Mack as control persons by virtue of their roles at Nantahala. The form attributes the same 6.90% percentage to each reporting person, reflecting joint attribution from the adviser relationship.
Any change in voting or disposition authority should appear in future filings; timing is not provided here.
Key Figures
Shares beneficially owned:1,360,419 sharesPercent of class:6.90%CUSIP:492327101+1 more
4 metrics
Shares beneficially owned1,360,419 sharesAs of March 31, 2026
Percent of class6.90%As of March 31, 2026
CUSIP492327101Keros Therapeutics Common Stock
Filing signature date05/15/2026Schedule signed by reporting persons
Key Terms
Schedule 13G, Beneficially owned, Shared dispositive power
3 terms
Schedule 13Gregulatory
"Each of Messrs. Harkey and Mack is filing this as a control person"
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.
Beneficially ownedfinancial
"Nantahala may be deemed to be the beneficial owner of 1,360,419 Shares"
Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.
Shared dispositive powerfinancial
"Shared dispositive power: 1,360,419 Shares"
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What stake did Nantahala report in KROS?
Nantahala reported beneficial ownership of 1,360,419 shares, equal to 6.90% of the outstanding common stock as of March 31, 2026. The shares are held by funds and separately managed accounts under Nantahala's control.
Do Harkey and Mack personally own the shares reported?
Messrs. Harkey and Mack are reported as control persons due to their roles at Nantahala and are attributed the 1,360,419 shares (6.90%). The filing states the shares are held by funds and accounts under Nantahala's control, with shared voting and dispositive power.
What voting or disposition powers are reported?
The schedule discloses 0 shares of sole voting or sole dispositive power and 1,360,419 shares of shared voting and shared dispositive power for each reporting person. This indicates joint control rather than exclusive authority over the shares.
When is the ownership figure effective?
The ownership figures are stated as of March 31, 2026. The Schedule 13G was signed on May 15, 2026, and reports the position held by Nantahala-controlled funds and accounts at the March 31, 2026 snapshot date.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Keros Therapeutics, Inc.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
492327101
(CUSIP Number)
03/31/2026
(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):
492327101
1
Names of Reporting Persons
Nantahala Capital Management, LLC
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
MASSACHUSETTS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,360,419.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,360,419.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,360,419.00
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)
6.90 %
12
Type of Reporting Person (See Instructions)
IA
SCHEDULE 13G
CUSIP Number(s):
492327101
1
Names of Reporting Persons
Wilmot B. Harkey
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
1,360,419.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,360,419.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,360,419.00
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)
6.90 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
492327101
1
Names of Reporting Persons
Daniel Mack
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
1,360,419.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,360,419.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,360,419.00
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)
6.90 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Keros Therapeutics, Inc.
(b)
Address of issuer's principal executive offices:
1050 WALTHAM STREET, SUITE 302 LEXINGTON, MASSACHUSETTS, 02421
Item 2.
(a)
Name of person filing:
(1) Nantahala Capital Management, LLC ("Nantahala")
(2) Wilmot B. Harkey
(3) Daniel Mack (together the "Reporting Persons")
(b)
Address or principal business office or, if none, residence:
130 Main St. 2nd Floor, New Canaan, Connecticut 06840
(c)
Citizenship:
(1) Nantahala is a Massachusetts limited liability company.
(2) Each of Messrs. Harkey and Mack is a citizen of the United States of America.
(d)
Title of class of securities:
Common Stock, $0.0001 par value per share
(e)
CUSIP Number(s):
492327101
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:
As of March 31, 2026, Nantahala may be deemed to be the beneficial owner of 1,360,419 Shares held by funds and separately managed accounts under its control, and as the managing members of Nantahala, each of Messrs. Harkey and Mack may be deemed to be a beneficial owner of those Shares.
(b)
Percent of class:
As of March 31, 2026, each of the Reporting Persons may be deemed to be the beneficial owner of the following percentage of the total number of Shares outstanding:
(1) Nantahala Capital Management, LLC ("Nantahala") : 6.90%
(2) Wilmot B. Harkey: 6.90%
(3) Daniel Mack: 6.90%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
(1) Nantahala Capital Management, LLC ("Nantahala") : 0 Shares.
(2) Wilmot B. Harkey: 0 Shares.
(3) Daniel Mack: 0 Shares.
(ii) Shared power to vote or to direct the vote:
(1) Nantahala Capital Management, LLC ("Nantahala") : 1,360,419 Shares.
(2) Wilmot B. Harkey: 1,360,419 Shares.
(3) Daniel Mack: 1,360,419 Shares.
(iii) Sole power to dispose or to direct the disposition of:
(1) Nantahala Capital Management, LLC ("Nantahala") : 0 Shares.
(2) Wilmot B. Harkey: 0 Shares.
(3) Daniel Mack: 0 Shares.
(iv) Shared power to dispose or to direct the disposition of:
(1) Nantahala Capital Management, LLC ("Nantahala") : 1,360,419 Shares.
(2) Wilmot B. Harkey: 1,360,419 Shares.
(3) Daniel Mack: 1,360,419 Shares.
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.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
Each of Messrs. Harkey and Mack is filing this Schedule 13G as a control person in respect of shares beneficially owned by Nantahala, an investment adviser as described in ss. 240.13d-1(b)(1)(ii)(E). See Item 4(a).
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 acquired and are held in the ordinary course of business and 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.
