MAD RIVER INVESTORS

Legal name: MRM-HORIZON ADVISORS, LLC

CRD 130585File 801-62991

APPROVED

Retail clients

Custody

Filing as of Jul 7, 2026

Feed vintage Aug 17, 2026

Regulatory AUM

$403.5M

Below cohort median (national)

Discretionary AUM

$403.5M

Clients

101

140 accounts

Employees

Below cohort median in MA

Identity & registration

ADV Item 1

Organization form: Limited Liability Company
Firm type: Registered
SEC region: BRO
Registration date: Apr 22, 2004
Principal office: 84 STATE STREET, SUITE 1060, BOSTON, MA, 02109
Phone: 617-728-0333
Website: HTTP://WWW.MRIVER.COM

Assets & accounts

ADV Item 5F

Total regulatory AUM: $403.5M
Discretionary AUM: $403.5M
Non-discretionary AUM: $0
Discretionary accounts: 140
Non-discretionary accounts: 0
Total accounts: 140
AUM per client: $4.0M

Clients by type

ADV Item 5D

Client type	Clients	AUM
Other	6	$26.4M
High net worth individuals	68	$269.2M
Pooled investment vehicles	2	$69.7M
Pension and profit sharing plans	4	$19.5M
Individuals (other than high net worth individuals)	21	$18.7M

Compensation & activities

ADV Items 5E, 5G

Compensation

Performance-based fees
A percentage of assets under your management

Advisory activities

Selection of other advisers
Portfolio management for businesses
Portfolio management for pooled investment vehicles
Portfolio management for individuals and/or small businesses

Custody

ADV Item 9

Firm Custody Cash: Yes
Firm Custody Assets: No
Firm Custody Clients: No
Firm Custody Securities: Yes
Related Person Custody Cash: No
Related Person Custody Assets: No
Related Person Custody Clients: No
Related Person Custody Securities: Yes

Disclosure events

ADV Item 11

This firm answered no to every Item 11 disclosure question in this filing.

Filed changes

Date	Field	From	To
Aug 12, 2026	Registration	—	APPROVED

Every value above is reproduced from this firm's Form ADV filing. Fields the firm left blank are shown as “Not reported” rather than filled in from other sources.