# EDGAR Filing Document

**Accession Number:** 0001096978
**File Stem:** 0001096978-25-000008
**Filing Date:** 2025-11
**Character Count:** 11457
**Document Hash:** 70ca37206cb1022b7c34bcb3a206ac19
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001096978-25-000008.hdr.sgml**: 20251114

**ACCESSION NUMBER**: 0001096978-25-000008

**CONFORMED SUBMISSION TYPE**: 13F-HR

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20250930

**FILED AS OF DATE**: 20251114

**DATE AS OF CHANGE**: 20251114

**EFFECTIVENESS DATE**: 20251114

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MARINER INVESTMENT GROUP LLC
- **CENTRAL INDEX KEY:** 0001096978

**ORGANIZATION NAME:**
- **EIN:** 510661527
- **STATE OF INCORPORATION:** DE

**FILING VALUES:**
- **FORM TYPE:** 13F-HR
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 028-11231
- **FILM NUMBER:** 251481871

**BUSINESS ADDRESS:**
- **STREET 1:** 500 MAMARONECK AVENUE, 4TH FLOOR
- **CITY:** HARRISON
- **STATE:** NY
- **ZIP:** 10528
- **BUSINESS PHONE:** 914-670-4300

**MAIL ADDRESS:**
- **STREET 1:** 500 MAMARONECK AVENUE, 4TH FLOOR
- **CITY:** HARRISON
- **STATE:** NY
- **ZIP:** 10528

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MARINER INVESTMENT GROUP INC
- **DATE OF NAME CHANGE:** 19991015

### FORM 13F COVER PAGE

**Report for the Calendar Year or Quarter Ended:** 09-30-2025

**Check here if Amendment** [ ] **Amendment Number:** 

**This Amendment (Check only one.):** [ ] is a restatement.

[ ] adds new holdings entries.

**Institutional Investment Manager Filing this Report:**

**Name:** MARINER INVESTMENT GROUP LLC<br>**Address:** 500 MAMARONECK AVENUE 4TH FLOOR<br>Harrison, NY 10528

**Form 13F File Number:** 028-11231

**CRD Number (if applicable):** 000124744

**SEC File Number (if applicable):** 801-62016

The institutional investment manager filing this report and the person by whom it is signed hereby represent that the person signing the report is authorized to submit it, that all information contained herein is true, correct and complete, and that it is understood that all required items, statements, schedules, lists, and tables, are considered integral parts of this form.

**Person Signing this Report on Behalf of Reporting Manager:**

**Name:** Patrick Beirne<br>**Title:** Chief Operating Officer<br>**Phone:** 914-670-4342

**Signature, Place, and Date of Signing:**

/s/  Patrick Beirne  New York, NY  10-22-2025<br>[Signature]  [City, State]  [Date]

**Report Type (Check only one.):**

[x] **13F HOLDINGS REPORT.** (Check here if all holdings of this reporting manager are reported in this report.)

[ ] **13F NOTICE.** (Check here if no holdings are reported in this report, and all holdings are reported by other reporting manager(s).)

[ ] **13F COMBINATION REPORT.** (Check here if a portion of the holdings for this reporting manager are reported in this report and a portion are reported by other reporting manager(s).)

### Form 13F Summary Page

**Report Summary:**

**Number of Other Included Managers:** 0

**Form 13F Information Table Entry Total:** 76

**Form 13F Information Table Value Total:** $330631531

      (round to nearest dollar)

**List of Other Included Managers:**

Provide a numbered list of the name(s) and Form 13F file number(s) of all institutional investment managers with respect to which this report is filed, other than the manager filing this report.

[If there are no entries in this list, state “NONE” and omit the column headings and list entries.]

**NONE**

### FORM 13F INFORMATION TABLE

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| NAME OF ISSUER | TITLE OF CLASS | CUSIP | FIGI | VALUE (x$1000) | SHRS OR PRN AMT | SH/PRN | PUT/CALL | INVESTMENT DISCRETION | OTHER MANAGER | VOTING AUTHORITY | VOTING AUTHORITY | VOTING AUTHORITY |
| NAME OF ISSUER | TITLE OF CLASS | CUSIP | FIGI | VALUE (x$1000) | SHRS OR PRN AMT | SH/PRN | PUT/CALL | INVESTMENT DISCRETION | OTHER MANAGER | SOLE | SHARED | NONE |
| ADVANCED MICRO DEVICES INC | COM | 007903107 |  | 2022375 | 12500 | SH |  | DFND |  | 12500 | 0 | 0 |
| ALIBABA GROUP HLDG LTD | NOTE 0.500% 6/0 | 01609WBG6 |  | 9197500 | 5000000 | PRN |  | DFND |  | 5000000 | 0 | 0 |
| ANTERO RESOURCES CORP | COM | 03674X106 |  | 37500 | 50000 | SH | Call | DFND |  | 50000 | 0 | 0 |
| APA CORPORATION | COM | 03743Q108 |  | 500000 | 100000 | SH | Call | DFND |  | 100000 | 0 | 0 |
| ARRAY DIGITAL INFRASTRUCTURE | COM | 911684108 |  | 1064813 | 21292 | SH |  | DFND |  | 21292 | 0 | 0 |
| BOLT PROJS HLDGS INC | *W EXP 08/13/202 | 09769B115 |  | 766 | 19150 | SH |  | DFND |  | 19150 | 0 | 0 |
| BOREALIS FOODS INC | *W EXP 02/07/202 | 09973D113 |  | 1782 | 23300 | SH |  | DFND |  | 23300 | 0 | 0 |
| BRIGHTHOUSE FINL INC | COM | 10922N103 |  | 7218880 | 136000 | SH |  | DFND |  | 136000 | 0 | 0 |
| BUILDERS FIRSTSOURCE INC | COM | 12008R107 |  | 495000 | 100000 | SH | Put | DFND |  | 100000 | 0 | 0 |
| CHEMOURS CO | COM | 163851108 |  | 871200 | 55000 | SH |  | DFND |  | 55000 | 0 | 0 |
| CHEMOURS CO | COM | 163851108 |  | 40000 | 50000 | SH | Call | DFND |  | 50000 | 0 | 0 |
| CHIMERA INVT CORP | COM SHS | 16934Q802 |  | 1520300 | 115000 | SH |  | DFND |  | 115000 | 0 | 0 |
| COGENT COMMUNICATIONS HLDGS | COM NEW | 19239V302 |  | 362250 | 105000 | SH | Put | DFND |  | 105000 | 0 | 0 |
| COMCAST CORP NEW | CL A | 20030N101 |  | 161400 | 120000 | SH | Put | DFND |  | 120000 | 0 | 0 |
| CONSTELLATION ENERGY CORP | COM | 21037T109 |  | 2665467 | 8100 | SH |  | DFND |  | 8100 | 0 | 0 |
| COREWEAVE INC | COM CL A | 21873S108 |  | 273700 | 2000 | SH |  | DFND |  | 2000 | 0 | 0 |
| CORNING INC | COM | 219350105 |  | 805000 | 200000 | SH | Call | DFND |  | 200000 | 0 | 0 |
| CRH PLC | ORD | G25508105 |  | 359700 | 3000 | SH |  | DFND |  | 3000 | 0 | 0 |
| CYCURION INC | *W EXP 02/13/203 | 95758L115 |  | 1212 | 30000 | SH |  | DFND |  | 30000 | 0 | 0 |
| DANA INC | COM | 235825205 |  | 200400 | 10000 | SH |  | DFND |  | 10000 | 0 | 0 |
| DOW INC | COM | 260557103 |  | 688388 | 433500 | SH | Put | DFND |  | 433500 | 0 | 0 |
| DOXIMITY INC | CL A | 26622P107 |  | 47002 | 40100 | SH | Put | DFND |  | 40100 | 0 | 0 |
| DUKE ENERGY CORP NEW | COM NEW | 26441C204 |  | 4950000 | 40000 | SH |  | DFND |  | 40000 | 0 | 0 |
| DUKE ENERGY CORP NEW | COM NEW | 26441C204 |  | 20000 | 25000 | SH | Call | DFND |  | 25000 | 0 | 0 |
| EATON VANCE MUN BD FD | COM | 27827X101 |  | 1161459 | 116847 | SH |  | DFND |  | 116847 | 0 | 0 |
| EDISON INTL | COM | 281020107 |  | 5063 | 22500 | SH | Put | DFND |  | 22500 | 0 | 0 |
| ENTERGY CORP NEW | COM | 29364G103 |  | 4193550 | 45000 | SH |  | DFND |  | 45000 | 0 | 0 |
| EQUINOR ASA | SPONSORED ADR | 29446M102 |  | 97500 | 100000 | SH | Call | DFND |  | 100000 | 0 | 0 |
| EXPRO GROUP HOLDINGS NV | COM | N3144W105 |  | 237600 | 20000 | SH |  | DFND |  | 20000 | 0 | 0 |
| FERGUSON ENTERPRISES INC | COMMON STOCK NEW | 31488V107 |  | 294500 | 70000 | SH | Call | DFND |  | 70000 | 0 | 0 |
| FLUOR CORP | NOTE 1.125% 8/1 | 343412AJ1 |  | 6063900 | 5100000 | PRN |  | DFND |  | 5100000 | 0 | 0 |
| FORD MTR CO | NOTE 3/1 | 345370CZ1 |  | 10160000 | 10000000 | PRN |  | DFND |  | 10000000 | 0 | 0 |
| FS KKR CAP CORP | COM | 302635206 |  | 332500 | 200000 | SH | Put | DFND |  | 200000 | 0 | 0 |
| ISHARES BITCOIN TRUST ETF | SHS BEN INT | 46438F101 |  | 130981110 | 2015094 | SH |  | DFND |  | 2015094 | 0 | 0 |
| ISHARES TR | EXPANDED TECH | 464287515 |  | 97500 | 50000 | SH | Put | DFND |  | 50000 | 0 | 0 |
| ISHARES TR | IBOXX HI YD ETF | 464288513 |  | 124132 | 506400 | SH | Put | DFND |  | 506400 | 0 | 0 |
| ISHARES TR | IBOXX INV CP ETF | 464287242 |  | 20956360 | 188000 | SH |  | DFND |  | 188000 | 0 | 0 |
| JD.COM INC | NOTE 0.250% 6/0 | 47215PAJ5 |  | 10770000 | 10000000 | PRN |  | DFND |  | 10000000 | 0 | 0 |
| KROGER CO | COM | 501044101 |  | 674100 | 10000 | SH |  | DFND |  | 10000 | 0 | 0 |
| LINCOLN ELEC HLDGS INC | COM | 533900106 |  | 3537450 | 15000 | SH |  | DFND |  | 15000 | 0 | 0 |
| LUMEN TECHNOLOGIES INC | COM | 550241103 |  | 459000 | 75000 | SH |  | DFND |  | 75000 | 0 | 0 |
| LYONDELLBASELL INDUSTRIES N | SHS - A - | N53745100 |  | 862500 | 200000 | SH | Put | DFND |  | 200000 | 0 | 0 |
| MARTIN MARIETTA MATLS INC | COM | 573284106 |  | 315140 | 500 | SH |  | DFND |  | 500 | 0 | 0 |
| MASTEC INC | COM | 576323109 |  | 340496 | 1600 | SH |  | DFND |  | 1600 | 0 | 0 |
| NEXTERA ENERGY CAP HLDGS INC | NOTE 3.000% 3/0 | 65339KCY4 |  | 11835000 | 10000000 | PRN |  | DFND |  | 10000000 | 0 | 0 |
| NOBLE CORP PLC | ORD SHS A | G65431127 |  | 282800 | 10000 | SH |  | DFND |  | 10000 | 0 | 0 |
| NUVEEN FLOATING RATE INCOME | COM | 67072T108 |  | 18463847 | 2257194 | SH |  | DFND |  | 2257194 | 0 | 0 |
| NVIDIA CORPORATION | COM | 67066G104 |  | 2500 | 100000 | SH | Put | DFND |  | 100000 | 0 | 0 |
| OLIN CORP | COM PAR $1 | 680665205 |  | 161250 | 100000 | SH | Put | DFND |  | 100000 | 0 | 0 |
| ON SEMICONDUCTOR CORP | NOTE 0.500% 3/0 | 682189AU9 |  | 4625856 | 5000000 | PRN |  | DFND |  | 5000000 | 0 | 0 |
| ONEOK INC NEW | COM | 682680103 |  | 175000 | 50000 | SH | Put | DFND |  | 50000 | 0 | 0 |
| PENNYMAC CORP | NOTE 8.500% 6/0 | 70932AAH6 |  | 1033500 | 1000000 | PRN |  | DFND |  | 1000000 | 0 | 0 |
| POST HLDGS INC | COM | 737446104 |  | 55000 | 50000 | SH | Put | DFND |  | 50000 | 0 | 0 |
| PROSHARES TR II | SHT VIX ST TRM | 74347W130 |  | 636750 | 12500 | SH |  | DFND |  | 12500 | 0 | 0 |
| RANGE RES CORP | COM | 75281A109 |  | 564600 | 15000 | SH |  | DFND |  | 15000 | 0 | 0 |
| RANGE RES CORP | COM | 75281A109 |  | 334125 | 285000 | SH | Call | DFND |  | 285000 | 0 | 0 |
| REDFIN CORP | NOTE 0.500% 4/0 | 75737FAE8 |  | 1527383 | 1645000 | PRN |  | DFND |  | 1645000 | 0 | 0 |
| REDWOOD TRUST INC | COM | 758075402 |  | 4906510 | 847411 | SH |  | DFND |  | 847411 | 0 | 0 |
| REDWOOD TRUST INC | NOTE 7.750% 6/1 | 758075AF2 |  | 3309900 | 3300000 | PRN |  | DFND |  | 3300000 | 0 | 0 |
| RITHM CAPITAL CORP | COM NEW | 64828T201 |  | 11105250 | 975000 | SH |  | DFND |  | 975000 | 0 | 0 |
| SELECT SECTOR SPDR TR | FINANCIAL | 81369Y605 |  | 31000 | 200000 | SH | Put | DFND |  | 200000 | 0 | 0 |
| SHIFT4 PMTS INC | CL A | 82452J109 |  | 3483000 | 45000 | SH |  | DFND |  | 45000 | 0 | 0 |
| SHUTTERSTOCK INC | COM | 825690100 |  | 335977 | 16114 | SH |  | DFND |  | 16114 | 0 | 0 |
| SNOWFLAKE INC | NOTE 10/0 | 833445AB5 |  | 7594315 | 5000000 | PRN |  | DFND |  | 5000000 | 0 | 0 |
| SPDR S 500 ETF TR | TR UNIT | 78462F103 |  | 25595968 | 38422 | SH |  | DFND |  | 38422 | 0 | 0 |
| SPDR S 500 ETF TR | TR UNIT | 78462F103 |  | 384825 | 335000 | SH | Put | DFND |  | 335000 | 0 | 0 |
| TRANSALTA CORP | COM | 89346D107 |  | 60000 | 100000 | SH | Call | DFND |  | 100000 | 0 | 0 |
| UNITED PARCEL SERVICE INC | CL B | 911312106 |  | 835300 | 10000 | SH |  | DFND |  | 10000 | 0 | 0 |
| UNITED PARCEL SERVICE INC | CL B | 911312106 |  | 445000 | 100000 | SH | Put | DFND |  | 100000 | 0 | 0 |
| VALMONT INDS INC | COM | 920253101 |  | 775460 | 2000 | SH |  | DFND |  | 2000 | 0 | 0 |
| VISTRA CORP | COM | 92840M102 |  | 2938800 | 15000 | SH |  | DFND |  | 15000 | 0 | 0 |
| VISTRA CORP | COM | 92840M102 |  | 363750 | 50000 | SH | Call | DFND |  | 50000 | 0 | 0 |
| VULCAN MATLS CO | COM | 929160109 |  | 307620 | 1000 | SH |  | DFND |  | 1000 | 0 | 0 |
| WILLIAMS COS INC | COM | 969457100 |  | 2534000 | 40000 | SH |  | DFND |  | 40000 | 0 | 0 |
| WILLIAMS COS INC | COM | 969457100 |  | 43750 | 50000 | SH | Call | DFND |  | 50000 | 0 | 0 |
| WOLFSPEED INC | COMMON STOCK | 97785W106 |  | 715000 | 25000 | SH |  | DFND |  | 25000 | 0 | 0 |

---