Mad River Investors, a Boston-based investment firm, has filed its Form 13F-HR report for the third quarter of 2026, disclosing its equity holdings as of September 30, 2026. The filing lists the firm's Chief Compliance Officer, Stephen C. Carluccio, as the authorized signatory.
The report details a portfolio of 35 distinct equity securities. The largest holding disclosed is Permidian Basin Royalty Trust Unit Beneficial Interest, for which Mad River holds 1,056,366 shares. The firm also holds significant positions in Landbridge Company LLC Class A (266,705 shares) and Waterbridge Infrastructure Limited Class A (268,751 shares).
The portfolio includes a mix of technology, healthcare, and energy companies. Major positions include Amazon.com Inc. (3,400 shares), Cisco Systems Inc. (6,000 shares), and Johnson & Johnson (1,200 shares). The firm also holds Grayscale Bitcoin Trust ETF Shares (355,444 shares) and Fidelity Wise Origin Bitcoin Shares (78,429 shares).
Other notable holdings include UnitedHealth Group Inc. (1,700 shares), Oracle Corp. (8,050 shares), and Palantir Technologies Inc. (5,484 shares). The filing also lists positions in Wheaton Precious Metals Corp. (45,024 shares) and Royal Gold Inc. (940 shares).
