# EDGAR Filing Document

**Accession Number:** 0001384484
**File Stem:** 0001384484-25-000009
**Filing Date:** 2025-10
**Character Count:** 7554
**Document Hash:** 07c5cc21c8c80aa6da8f84163e12df19
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001384484-25-000009.hdr.sgml**: 20251014

**ACCESSION NUMBER**: 0001384484-25-000009

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

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20250930

**FILED AS OF DATE**: 20251014

**DATE AS OF CHANGE**: 20251014

**EFFECTIVENESS DATE**: 20251014

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MAD RIVER INVESTORS
- **CENTRAL INDEX KEY:** 0001384484

**ORGANIZATION NAME:**
- **EIN:** 043446822
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 13F-HR
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 028-12322
- **FILM NUMBER:** 251389891

**BUSINESS ADDRESS:**
- **STREET 1:** 84 STATE STREET
- **STREET 2:** SUITE 1060
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109
- **BUSINESS PHONE:** 617-728-0333

**MAIL ADDRESS:**
- **STREET 1:** 84 STATE STREET
- **STREET 2:** SUITE 1060
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MRM-Horizon Advisors LLC
- **DATE OF NAME CHANGE:** 20061222

### 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:** MAD RIVER INVESTORS<br>**Address:** 84 STATE STREET<br>SUITE 1060<br>BOSTON, MA 02109

**Form 13F File Number:** 028-12322

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:** Stephen C. Carluccio<br>**Title:** Chief Compliance Officer<br>**Phone:** 617-531-1739

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

/Stephen C. Carluccio/  Boston, MA  10-14-2025<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:** 38

**Form 13F Information Table Value Total:** $233754396

      (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 |
| AMAZON COM INC | COM | 023135106 |  | 746538 | 3400 | SH |  | SOLE |  | 0 | 0 | 3400 |
| APPLE INC | COM | 037833100 |  | 1273150 | 5000 | SH |  | SOLE |  | 0 | 0 | 5000 |
| BERKSHIRE HATHAWAY INC DEL | CL B NEW | 084670702 |  | 590720 | 1175 | SH |  | SOLE |  | 0 | 0 | 1175 |
| CACI INTL INC | CL A | 127190304 |  | 401518 | 805 | SH |  | SOLE |  | 0 | 0 | 805 |
| CARNIVAL CORP | UNIT 99/99/9999 | 143658300 |  | 4492506 | 155396 | SH |  | SOLE |  | 0 | 0 | 155396 |
| CBOE GLOBAL MKTS INC | COM | 12503M108 |  | 1632054 | 6655 | SH |  | SOLE |  | 0 | 0 | 6655 |
| CINCINNATI FINL CORP | COM | 172062101 |  | 569160 | 3600 | SH |  | SOLE |  | 0 | 0 | 3600 |
| CISCO SYS INC | COM | 17275R102 |  | 410520 | 6000 | SH |  | SOLE |  | 0 | 0 | 6000 |
| CITIGROUP INC | COM NEW | 172967424 |  | 304500 | 3000 | SH |  | SOLE |  | 0 | 0 | 3000 |
| EATON CORP PLC | SHS | G29183103 |  | 449100 | 1200 | SH |  | SOLE |  | 0 | 0 | 1200 |
| FIDELITY WISE ORIGIN BITCOIN | SHS | 315948109 |  | 7166757 | 71804 | SH |  | SOLE |  | 0 | 0 | 71804 |
| FIRSTENERGY CORP | COM | 337932107 |  | 261174 | 5700 | SH |  | SOLE |  | 0 | 0 | 5700 |
| FRANCO NEV CORP | COM | 351858105 |  | 5255925 | 23579 | SH |  | SOLE |  | 0 | 0 | 23579 |
| GAMING  LEISURE PPTYS INC | COM | 36467J108 |  | 212449 | 4558 | SH |  | SOLE |  | 0 | 0 | 4558 |
| GRAYSCALE BITCOIN MINI TR ET | SHS NEW | 389930207 |  | 4160723 | 82179 | SH |  | SOLE |  | 16568 | 0 | 65611 |
| GRAYSCALE BITCOIN TRUST ETF | SHS REP COM UT | 389637109 |  | 32402841 | 360954 | SH |  | SOLE |  | 68200 | 0 | 292754 |
| HAWAIIAN ELEC INDUSTRIES | COM | 419870100 |  | 13581960 | 1230250 | SH |  | SOLE |  | 0 | 0 | 1230250 |
| INTERCONTINENTAL EXCHANGE IN | COM | 45866F104 |  | 1300733 | 7720 | SH |  | SOLE |  | 0 | 0 | 7720 |
| INVESCO EXCHANGE TRADED FD T | S EQL WGT | 46137V357 |  | 286068 | 1508 | SH |  | SOLE |  | 0 | 0 | 1508 |
| JOHNSON  JOHNSON | COM | 478160104 |  | 222504 | 1200 | SH |  | SOLE |  | 0 | 0 | 1200 |
| JPMORGAN CHASE  CO. | COM | 46625H100 |  | 441602 | 1400 | SH |  | SOLE |  | 0 | 0 | 1400 |
| KIMBERLY-CLARK CORP | COM | 494368103 |  | 348152 | 2800 | SH |  | SOLE |  | 0 | 0 | 2800 |
| LANDBRIDGE COMPANY LLC | CL A | 514952100 |  | 12860359 | 241056 | SH |  | SOLE |  | 0 | 0 | 241056 |
| MESABI TR | CTF BEN INT | 590672101 |  | 8649963 | 295523 | SH |  | SOLE |  | 0 | 0 | 295523 |
| MIAMI INTL HLDGS INC | COM | 59356Q108 |  | 3003396 | 74600 | SH |  | SOLE |  | 0 | 0 | 74600 |
| ORACLE CORP | COM | 68389X105 |  | 2263982 | 8050 | SH |  | SOLE |  | 0 | 0 | 8050 |
| PALO ALTO NETWORKS INC | COM | 697435105 |  | 1116653 | 5484 | SH |  | SOLE |  | 0 | 0 | 5484 |
| PERMIAN BASIN RTY TR | UNIT BEN INT | 714236106 |  | 16830700 | 922230 | SH |  | SOLE |  | 0 | 0 | 922230 |
| RLI CORP | COM | 749607107 |  | 489150 | 7500 | SH |  | SOLE |  | 0 | 0 | 7500 |
| SALESFORCE INC | COM | 79466L302 |  | 213300 | 900 | SH |  | SOLE |  | 0 | 0 | 900 |
| SANDSTORM GOLD LTD | COM NEW | 80013R206 |  | 533252 | 42592 | SH |  | SOLE |  | 0 | 0 | 42592 |
| TEXAS PACIFIC LAND CORPORATI | COM | 88262P102 |  | 88483336 | 94772 | SH |  | SOLE |  | 0 | 0 | 94772 |
| TEXAS PACIFIC LAND CORPORATI | PUT | 88262P102 |  | 373456 | 400 | PRN | Put | SOLE |  | 0 | 0 | 400 |
| UNITEDHEALTH GROUP INC | COM | 91324P102 |  | 587010 | 1700 | SH |  | SOLE |  | 0 | 0 | 1700 |
| VANGUARD INDEX FDS | TOTAL STK MKT | 922908769 |  | 3978077 | 12122 | SH |  | SOLE |  | 0 | 0 | 12122 |
| VANGUARD SPECIALIZED FUNDS | DIV APP ETF | 921908844 |  | 561054 | 2600 | SH |  | SOLE |  | 0 | 0 | 2600 |
| WATERBRIDGE INFRASTRUCTURE L | CL A SHS REPSTG | 940923105 |  | 6347874 | 251700 | SH |  | SOLE |  | 0 | 0 | 251700 |
| WHEATON PRECIOUS METALS CORP | COM | 962879102 |  | 10952180 | 97927 | SH |  | SOLE |  | 0 | 0 | 97927 |

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