# EDGAR Filing Document

**Accession Number:** 0000874501
**File Stem:** 0001707461-26-000002
**Filing Date:** 2026-3
**Character Count:** 8113
**Document Hash:** 4ac7d7b86100b1eb1037187d26ce02ff
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001707461-26-000002.hdr.sgml**: 20260303

**ACCESSION NUMBER**: 0001707461-26-000002

**CONFORMED SUBMISSION TYPE**: 4/A

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250929

**FILED AS OF DATE**: 20260303

**DATE AS OF CHANGE**: 20260303

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Smith R Sharon
- **CENTRAL INDEX KEY:** 0001707461

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-10777
- **FILM NUMBER:** 26715829

**MAIL ADDRESS:**
- **STREET 1:** 40 WALL STREET
- **STREET 2:** 55TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10005
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** OCTAVE SPECIALTY GROUP INC
- **CENTRAL INDEX KEY:** 0000874501
- **STANDARD INDUSTRIAL CLASSIFICATION:** SURETY INSURANCE [6351]
- **ORGANIZATION NAME:** 02 Finance
- **EIN:** 133621676
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 40 WALL STREET
- **STREET 2:** 55TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10005
- **BUSINESS PHONE:** 2126587470

**MAIL ADDRESS:**
- **STREET 1:** 40 WALL STREET
- **STREET 2:** 55TH FLOOR
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10005

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** AMBAC FINANCIAL GROUP INC
- **DATE OF NAME CHANGE:** 19980121

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** AMBAC INC /DE/
- **DATE OF NAME CHANGE:** 19930328

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4/A

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Smith R Sharon<br><sub>(Last) (First) (Middle)</sub><br>OCTAVE SPECIALTY GROUP, INC.<br>40 WALL STREET, 55TH FLOOR<br><sub>(Street)</sub><br>NEW YORK, NY 10005<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-29 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_Exec VP & Group COO_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>OCTAVE SPECIALTY GROUP INC [ OSG ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-09-29 |  | C |  | 145135<sup>(1)</sup> | A | $0 | 219842 | D |  |
| Common Stock | 2025-09-29 |  | F |  | 70680<sup>(2)</sup> | D | $9.72 | 149162 | D |  |
| Common Stock | 2025-09-30 |  | M |  | 3235<sup>(3)</sup> | A | $0 | 152397 | D |  |
| Common Stock | 2025-09-30 |  | F |  | 3235<sup>(4)</sup> | D | $8.34 | 149162 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Deferred Share Units | <sup>(5)</sup> | 2025-09-29 |  | C |  |  | 145135 | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 145135 | $0 | 0 | D |  |
| Deferred Share Units | <sup>(5)</sup> | 2025-09-30 |  | A |  | 76206 |  | <sup>(6)</sup> | <sup>(6)</sup> | Common Stock | 76206 | $0 | 76206 | D |  |

---

### Footnotes:

(1) Upon the closing of the sale of Ambac Assurance Corporation by Ambac Financial Group to an entity owned by funds managed by Oaktree Capital Management, L.P., a change of control was triggered causing the Reporting Person's Deferred Share Units ("DSUs") to vest and settle.

(2) Represents the corrected amount of DSUs that were converted into shares of common stock and withheld by the Company to satisfy certain tax withholding obligations.

(3) On September 30, 2025 the Compensation Committee of the Board of Directors of Ambac Financial Group approved the acceleration of the Reporting Person's 2023 and 2024 Performance Stock Unit awards in connection with the change of control referred to in footnote 1.  The reporting person acquired  shares of common stock of Ambac Financial Group, Inc. (the "Company") upon the simultaneous vesting and settlement of the reporting person's 2023 and 2024 Long Term Incentive Plan PSU awards.

(4) Represents the corrected aggregate amount of PSUs that were converted into shares of common stock and withheld by the Company to satisfy certain tax withholding obligations.

(5) Each DSU represents a contingent right to receive one share of common stock of the Company.

(6) Represents the aggregate amount of performance stock units ("PSUs") that were converted into an equivalent number of DSUs pursuant to the Company's Executive Stock Deferral Plan, which was designed to enable participants to elect to defer the settlement and income taxation of PSU and restricted stock unit awards in accordance with Section 409A of the Internal Revenue Code of 1986, as amended.

**Remarks:**
This amended Form 4 was filed to correct an error in the calculation of the number of shares required to be withheld by the Company to satisfy certain tax withholding obligations.

**Signature:** William White, attorney-in-fact  
**Date:** 2026-03-03

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**