ATTACHMENTS / EXHIBITS

SCHEDULE 13D

CUSIP No.

492327101

1

Name of reporting person

ADAR1 Capital Management, 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

TEXAS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 5,390,964.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 5,390,964.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

5,390,964.00

12

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

13

Percent of class represented by amount in Row (11)

13.27 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

The amounts reported in boxes 7, 9 and 11 include (i) 4,392,737 shares of Common Stock held by ADAR1 Partners, LP, (ii) 743,558 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC and (iii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of May 12, 2025. As the investment manager of ADAR1 Partners, LP and ADAR1 SPV I, LP and as the sub-advisor of Spearhead Insurance Solutions IDF, LLC, ADAR1 Capital Management, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC. Amounts reported do not include shares underlying certain put options and swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of May 1, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed with the SEC on May 6, 2025.

SCHEDULE 13D

CUSIP No.

492327101

1

Name of reporting person

ADAR1 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

TEXAS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 4,647,406.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 4,647,406.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

4,647,406.00

12

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

13

Percent of class represented by amount in Row (11)

11.44 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

The amounts reported in boxes 7, 9 and 11 include (i) 4,392,737 shares of Common Stock held by ADAR1 Partners, LP and (ii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of May 12, 2025. As the general partner of ADAR1 Partners, LP and ADAR1 SPV I, LP, ADAR1 Capital Management GP, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP and ADAR1 SPV I, LP. Amounts reported do not include shares underlying certain put options and swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of May 1, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed with the SEC on May 6, 2025.

SCHEDULE 13D

CUSIP No.

492327101

1

Name of reporting person

Daniel Schneeberger

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

TEXAS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 5,390,964.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 5,390,964.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

5,390,964.00

12

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

13

Percent of class represented by amount in Row (11)

13.27 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The amounts reported in boxes 7, 9 and 11 include (i) 4,392,737 shares of Common Stock held by ADAR1 Partners, LP, (ii) 743,558 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC and (iii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of May 12, 2025. As the manager of ADAR1 Capital Management, LLC and ADAR1 Capital Management GP, LLC, Mr. Schneeberger may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP, Spearhead Insurance Solutions IDF, LLC, and ADAR1 SPV I, LP. Amounts reported do not include shares underlying certain put options and swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of May 1, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed with the SEC on May 6, 2025.

SCHEDULE 13D

Item 1.

Security and Issuer

(a)

Title of Class of Securities:

Common Stock, $0.0001 par value per share

(b)

Name of Issuer:

Keros Therapeutics, Inc.

(c)

Address of Issuer's Principal Executive Offices:

1050 WALTHAM STREET, SUITE 302, LEXINGTON, MASSACHUSETTS , 02421.

Item 1 Comment:

This Amendment No. 3 ("Amendment No. 3") amends and supplements the statement on Schedule 13D filed with the Securities and Exchange Commission on April 11, 2025 (as amended from time to time, the "Schedule 13D"). Except as otherwise stated, the Schedule 13D remains unchanged. Capitalized terms used herein and not otherwise defined in this Amendment No. 3 have the meanings set forth in the Schedule 13D.

Item 4.

Purpose of Transaction

On May 12, 2025, ADAR1 Capital Management issued a press release (the "May 12 Press Release") including a presentation (the "May 12 Presentation") outlining its proposals to maximize value for the Issuer's stockholders, including (i) restructuring the business and reducing costs, (ii) returning excess cash to stockholders, and (iii) optimizing value of the Issuer's partnership with Takeda Pharmaceuticals, and reiterating its intention to vote "WITHHOLD" on the re-election of Dr. Mary Ann Gray and Dr. Alpna Seth to the Board at the Annual Meeting. The foregoing descriptions of the May 12 Press Release and the May 12 Presentation do not purport to be complete and are qualified in their entirety by reference to the full texts of the May 12 Press Release and the May 12 Presentation, which are attached hereto as Exhibit F and Exhibit G, respectively, and are incorporated herein by reference.

Item 7.

Material to be Filed as Exhibits.

Exhibit F: May 12 Press Release Exhibit G: May 12 Presentation

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.

ADAR1 Capital Management, LLC

Signature:	/s/ Daniel Schneeberger
Name/Title:	Daniel Schneeberger, Manager
Date:	05/12/2025

ADAR1 Capital Management GP, LLC

Signature:	/s/ Daniel Schneeberger
Name/Title:	Daniel Schneeberger, Manager
Date:	05/12/2025

Daniel Schneeberger

Signature:	/s/ Daniel Schneeberger
Name/Title:	Daniel Schneeberger
Date:	05/12/2025