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A.G. Hill Partners
Al G. Hill Jr. built his Dallas single-family office in 2009 on the H.L.
A.G. Hill Partners
A.G. Hill Partners was established in 2009 by Al G. Hill Jr., the eldest grandson of oil wildcatter H.L. Hunt, to unify the investment activities of his branch of the family. The office grew out of a period of protracted intra-family litigation resolved around 2010, after which the Hill Jr. family consolidated its assets under a formal single-family office structure. Today the firm sits in Dallas, with Joseph D. O'Brien III serving as President and CEO to oversee the operational and investment functions. The firm's capital is allocated across real estate, private equity, venture capital, direct co-investments, and public securities. Real estate forms the most visible concentration — the portfolio includes Highland Park Village in Dallas, Country Club Plaza in Kansas City, and Phillips Place in Charlotte. On the private equity side, A.G. Hill Partners participates in consortium deals: in 2023 it joined the PW Consortium alongside Cain Capital, Fortress Investment Group, HF Capital, and Petro-Hunt to acquire PureWest Energy, a deal that The Energy Council named North American Deal of the Year (per Altss estimate). The firm invests across early-stage, growth, and buyout transactions, and maintains a fund-of-funds program alongside its direct activity. Its geographic focus remains North America. Team size is not publicly disclosed, though key personnel include CFO Mandy de Turck Norris, who was promoted to President in April 2025 while continuing her CFO duties. That same month, the office restructured, launching two affiliated family offices — Starhill Holdings for the Summers family and Gillon Capital for the Washburne family — with A.G. Hill Partners providing shared accounting, legal, and family-management services to both. The restructuring decouples the branches operationally while preserving central infrastructure. Philanthropy runs through the Trinity Family Foundation, led by Heather Hill Washburne and Elisa Hill Summers, both daughters of Al G. Hill Jr. The firm's structural differentiator is its transition from a consolidated Hunt-Hill patrimony into a multi-entity architecture that separates investment management from family governance. By launching Gillon Capital and Starhill Holdings as distinct family offices with shared back-office support, A.G. Hill Partners permits each branch to pursue independent investment postures without duplicating overhead — a design suited to intergenerational wealth where family members are active operators in their own right. This architecture separates A.G. Hill Partners from the classic centralized family-office model and from the arms-length multi-family-office approach.
General information
Firm type
Single Family Office
Year founded
2009
AUM
Undisclosed
Location
Region
North America
Country
United States
City
Dallas
Corporate office
Dallas, TX, United States
Principals
Al G. Hill Jr.
Founder
Joseph D. O'Brien III
President and CEO
Mandy de Turck Norris
President & CFO
Sector focus
Frequently asked questions
Who runs investment decisions at A.G. Hill Partners?
Joseph D. O'Brien III serves as President and CEO, leading the firm's investment and operational activities. Mandy de Turck Norris, promoted to President in April 2025, oversees financial operations as CFO. The firm historically included an Investment Committee on which J. Keith Benedict served before he departed to become CEO of South Summit Capital.
Where does the underlying wealth come from?
The wealth originates with H.L. Hunt, the Texas oil wildcatter whose fortune was among the largest in the United States. Al G. Hill Jr. is Hunt's eldest grandson and consolidated his branch of the inheritance after a period of family litigation resolved around 2010. The firm manages assets generated by the Hunt oil legacy and subsequent investments.
How is A.G. Hill Partners related to Gillon Capital and Starhill Holdings?
In April 2025, A.G. Hill Partners restructured to launch two affiliated single-family offices: Gillon Capital for the Washburne family and Starhill Holdings for the Summers family. Both are distinct legal entities with their own investment postures, but A.G. Hill Partners provides shared services — accounting, legal, and family management — to each. The name Gillon Capital echoes the family's real estate operating company, Gillon Property Group.
Does A.G. Hill Partners participate in fund commitments or only direct deals?
The firm does both. Its investment types include direct co-investments and SPVs, fund-of-fund commitments, and direct real estate holdings. In 2023, it joined a consortium of co-investors including Fortress Investment Group and HF Capital to acquire PureWest Energy, illustrating its appetite for direct consortium transactions alongside fund partnerships.
What investment stages does the firm typically target?
A.G. Hill Partners invests across a wide range of stages, including early-stage, growth equity, middle market, and buyout transactions. Its venture capital activity focuses on early-stage and growth deals, while private equity commitments extend to buyout and middle-market investments, always through a North American lens.
How does the firm handle philanthropy and family governance?
Philanthropy is concentrated in the Trinity Family Foundation, led by Heather Hill Washburne and Elisa Hill Summers, both daughters of Al G. Hill Jr. The foundation supports causes in education and community development, with known donations to Southern Methodist University, VNA Texas, and TREC Community Investors. Governance is evolving through the 2025 restructuring, which formally separates the Summers and Washburne branches into dedicated family offices while retaining shared infrastructure.
Is A.G. Hill Partners still operating under that name?
Yes and no. The legal entity — A.G. Hill Partners, LLC — continues to operate and provide services to the newly formed Gillon Capital and Starhill Holdings. As of late 2025, the firm is also operating under the Gillon Capital name for certain activities. The dual naming reflects the current multi-entity architecture rather than a wholesale rebrand.
Profile maintained by Altss using OSINT (open-source intelligence), regulatory filings, licensed data partners, and verified direct submissions. Read the methodology. Last updated: . Continuous refresh with full update cycles at least every 30 days.
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