Data / Investment advisers / Massachusetts / Mad River Investors
Mad River Investors, Boston, MA: $404 million AUM, SEC registered investment adviser
Updated November 7, 2026. Source: the SEC's Form ADV data files for investment advisers.
Mad River Investors is an SEC registered investment adviser with its main office in Boston, Massachusetts and reports $404 million in regulatory assets under management in its Form ADV filed July 7, 2026. Its clients include high net worth individuals, pooled investment vehicles and corporations and other businesses. It is paid through a percentage of assets under management and performance based fees. It advises 2 private funds.
The request: Watch Mad River Investors (CRD number 130585): each new Form ADV amendment, with AUM, clients and private funds. $10 of work on sign-up, no card.
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- Registration
- SEC registered investment adviser
- CRD number
- 130585
- SEC file number
- 801-62991
- SEC status
- Approved, effective April 22, 2004
- Legal name
- Mrm-Horizon Advisors, LLC
- Main office
- 84 State Street, Suite 1060, Boston, MA 02109
- Phone
- (617) 728-0333
- Website
- mriver.com
- Regulatory AUM
- $403,531,748 in the Form ADV filed July 7, 2026
- Discretionary AUM
- $403,531,748
- Accounts
- 140
- Employees
- 6, of which 2 give investment advice
- Form of organization
- Limited Liability Company
- Paid through
- a percentage of assets under management, performance based fees
- Private funds
- 2: 2 hedge funds
- Gross assets of private funds
- $69,708,458
- Other offices
- 1
- Form ADV Item 11 disclosures
- None reported
- Latest Form ADV filing
- July 7, 2026
- SEC record
- Investment Adviser Public Disclosure
Clients
Client types the adviser reports in Form ADV item 5.D, with the AUM it attributes to each.
| Client type | Clients | AUM |
|---|---|---|
| High net worth individuals | 68 | $269.2 million |
| Pooled investment vehicles | 2 | $69.7 million |
| Corporations or other businesses | 6 | $26.4 million |
| Pension and profit sharing plans | 4 | $19.5 million |
| Individuals (other than high net worth individuals) | 21 | $18.7 million |
AUM in the SEC's monthly files
Each change in the AUM the adviser reported across the monthly SEC files held here, with the first file that shows the new value.
| First in the file of | AUM | Form ADV filed |
|---|---|---|
| April 1, 2026 | $403.5 million | March 27, 2026 |
| December 1, 2025 | $338.3 million | March 28, 2025 |
Other advisers in Boston
| Adviser | City | AUM | Private funds | Source |
|---|---|---|---|---|
| McCarter Private Wealth Services LLC | Boston | $427.7 million | Not listed | adviserinfo.sec.gov |
| Spring Lane Capital | Boston | $424.7 million | 7 | adviserinfo.sec.gov |
| Emblem Group, L.P. | Boston | $419.4 million | 5 | adviserinfo.sec.gov |
| Summit Partners Credit Advisors, L.P. | Boston | $419 million | 8 | adviserinfo.sec.gov |
| Clean Energy Venture Management, LLC | Boston | $416.4 million | 2 | adviserinfo.sec.gov |
| Century Equity Partners LLC | Boston | $378.3 million | 6 | adviserinfo.sec.gov |
| Donoghue Forlines LLC | Boston | $370.5 million | Not listed | adviserinfo.sec.gov |
| Crawford Fund Management, LLC | Boston | $356.1 million | 1 | adviserinfo.sec.gov |
Also on SpecStream
- Investment advisers in Boston, MA
- Investment advisers in Massachusetts
- Advisers with $100 million to $500 million in AUM
- Advisers serving high net worth individuals
- Advisers serving pooled investment vehicles
- Advisers that manage private funds
- Mad River Investors on the SEC's adviser search
Public data published by the US Securities and Exchange Commission (US government work). Advisers report these values themselves in Form ADV, and neither the SEC nor the states approve or guarantee them. AUM is regulatory assets under management as the adviser reported it in Form ADV item 5.F, which can differ from the AUM a firm quotes elsewhere. Exempt reporting advisers do not report AUM. Office address, phone and website are the adviser's main office as filed; a firm that files its main office as a private residence shows no street address or phone. An Item 11 disclosure is a reported event, not a finding about the firm today. Details for each firm are on the SEC's Investment Adviser Public Disclosure site. This page uses SEC data and is not endorsed or certified by the SEC. Free to reuse with credit to SpecStream under CC BY 4.0. Spot a wrong value? Write to [email protected] with the link to this page.