Insider filing report for Changes in Beneficial Ownership
- Schedule 13G & 13D forms are used to report a party's ownership of stock which exceeds 5% of a company's total stock issue.
- Schedule 13G is a shorter version of Schedule 13D with fewer reporting requirements.
"Insiders might sell their shares for any number of reasons, but they buy them for only one: they think the price will rise"
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 |
SCHEDULE 13G
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UNDER THE SECURITIES EXCHANGE ACT OF 1934
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Mereo BioPharma Group plc (Name of Issuer) |
American Depositary Shares, each representing five ordinary shares, nominal value of 0.003 GBP per share (Title of Class of Securities) |
589492107 (CUSIP Number) |
12/29/2025 (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)
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 Rule 13d-1(c)
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| Rule 13d-1(d)
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SCHEDULE 13G
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| CUSIP No. | 589492107 |
| 1 | Names of Reporting Persons
683 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
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 9 | Aggregate Amount Beneficially Owned by Each Reporting Person
65,083,815.00 | ||||||||
| 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)
8.18 % | ||||||||
| 12 | Type of Reporting Person (See Instructions)
IA |
SCHEDULE 13G
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| CUSIP No. | 589492107 |
| 1 | Names of Reporting Persons
683 Capital Partners, LP | ||||||||
| 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
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 9 | Aggregate Amount Beneficially Owned by Each Reporting Person
65,083,815.00 | ||||||||
| 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)
8.18 % | ||||||||
| 12 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13G
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| CUSIP No. | 589492107 |
| 1 | Names of Reporting Persons
Ari Zweiman | ||||||||
| 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 9 | Aggregate Amount Beneficially Owned by Each Reporting Person
65,083,815.00 | ||||||||
| 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)
8.18 % | ||||||||
| 12 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13G
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| Item 1. | ||
| (a) | Name of issuer:
Mereo BioPharma Group plc | |
| (b) | Address of issuer's principal executive offices:
ONE CAVENDISH PLACE, FOURTH FLOOR, LONDON, UNITED KINGDOM W1G 0QF | |
| Item 2. | ||
| (a) | Name of person filing:
683 Capital Management, LLC 683 Capital Partners, LP Ari Zweiman | |
| (b) | Address or principal business office or, if none, residence:
The principal business address for each of the Reporting Persons is 1700 Broadway, Suite 4200, New York, New York 10019. | |
| (c) | Citizenship:
683 Capital Management, LLC - DELAWARE 683 Capital Partners, LP - DELAWARE Ari Zweiman - UNITED STATES | |
| (d) | Title of class of securities:
American Depositary Shares, each representing five ordinary shares, nominal value of 0.003 GBP per share | |
| (e) | CUSIP No.:
589492107 | |
| 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);
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| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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| (c) | Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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| (e) | An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
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| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
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| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
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| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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| (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);
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| (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:
CUSIP 589492107 relates to the American Depositary Shares, each representing five ordinary shares, nominal value of GBP 0.003 per share. As of January 6, 2026, 683 Capital Partners, LP beneficially owned 65,083,815 Ordinary Shares represented by 13,016,763 ADS. 683 Capital Management, LLC, as the investment manager of 683 Capital Partners, LP, may be deemed to have beneficially owned the 65,083,815 Ordinary Shares beneficially owned by 683 Capital Partners, LP. Ari Zweiman, as the Managing Member of 683 Capital Management, LLC, may be deemed to have beneficially owned the 65,083,815 Ordinary Shares beneficially owned by 683 Capital Management, LLC. The following percentage is based on 795,658,504 Ordinary Shares (GBP 0.003 par value per share) outstanding as of November 7, 2025, as disclosed in the Issuer's Form 10-Q filed on November 10, 2025. As of January 6, 2026, the Reporting Persons may be deemed to have beneficially owned approximately 8.18% of the outstanding Ordinary Shares. | |
| (b) | Percent of class:
8.18 %
| |
| (c) | Number of shares as to which the person has:
| |
| (i) Sole power to vote or to direct the vote:
See Cover Pages Items 5-9. | ||
| (ii) Shared power to vote or to direct the vote:
See Cover Pages Items 5-9. | ||
| (iii) Sole power to dispose or to direct the disposition of:
See Cover Pages Items 5-9. | ||
| (iv) Shared power to dispose or to direct the disposition of:
See Cover Pages Items 5-9. | ||
| Item 5. | Ownership of 5 Percent or Less of a Class. | |
| 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
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| Item 8. | Identification and Classification of Members of the Group. | |
If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group.
See Exhibit A. | ||
| Item 9. | Notice of Dissolution of Group. | |
Not Applicable
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| 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.
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Exhibit Information
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JOINT FILING AGREEMENT The undersigned hereby agree that the statement on Schedule 13G with respect to the Ordinary Shares, par value 0.003 GBP per share, of Mereo BioPharma Group plc dated as of January 6, 2026 is, and any further amendments thereto signed by each of the undersigned shall be, filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k)(2) under the Securities Exchange Act of 1934, as amended. Dated: January 6, 2026 683 CAPITAL MANAGEMENT, LLC By: /s/ Ari Zweiman Ari Zweiman, Managing Member 683 CAPITAL PARTNERS, LP By: /s/ Ari Zweiman Ari Zweiman, Authorized Person /s/ Ari Zweiman Ari Zweiman |