Faculty

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Jeff Sandefer

Entrepreneur | Educator | Co-Founder, Acton School of Business

Jeff built Sandefer Offshore into an oil-and-gas company that generated more than $500 million in profits in under five years before leading a multi-billion-dollar energy firm. A five-time recipient of UT Austin’s outstanding teacher award, he went on to co-found Acton School of Business and Acton Academy. He brings rare experience from both sides of the classroom: building successful businesses and developing entrepreneurs.

Jack Long

Entrepreneur | Co-Founder, Lone Star Overnight & PeopleAdmin

Jack co-founded two Inc. 500 companies: Lone Star Overnight and PeopleAdmin, a software company that grew to serve more than 700 organizations before its acquisition by Vista Equity Partners. He later taught entrepreneurship in the UT Austin MBA program and joined Acton’s founding faculty. Jack brings firsthand experience in launching, scaling, and exiting companies across very different industries.

Steven Tomlinson

Entrepreneurial Communication | Founding Acton Master Teacher

Steven spent 17 years teaching economics and finance at UT Austin and designed and directed its MBA professional development program. A Stanford-trained economist and founding Acton master teacher, he has coached Fortune 500 leaders, Wall Street executives, and startup founders on leadership and communication. His work focuses on a skill every entrepreneur eventually needs: turning complex thinking into a clear, compelling message others can act on.

Kimberly Watson-Hemphill

Founder, Firefly Consulting | Operations & Innovation Expert

Kimberly founded Firefly Consulting after leadership roles at Accenture and George Group Consulting. She has led operational improvement work for Fortune 500 companies across the U.S., Europe, and Asia, with Lean Six Sigma deployments generating more than $1 billion in savings. She co-authored Fast Innovation, named to BusinessWeek’s Top 10 business-book list, and is an accomplished author and longtime Acton instructor. Kimberly brings deep expertise in turning complex operations into systems that create greater speed, margin, and resilience.

Jeff Serra

Entrepreneur | Investor | Former Acton Master Teacher

Jeff founded and sold four companies over a 35-year career spanning energy, renewable energy, and private credit. He led Phibro Energy before its sale to Valero, built and sold a renewable-energy company for $125 million, and later co-founded Vida Capital with Phil Siegel and sold for over a half a billion dollars in 2019. A former Acton master teacher, Jeff brings experience across the full entrepreneurial cycle: building, operating, selling, investing, and starting again.

Phil Siegel

Founder & Managing Partner, Tritium Partners

Phil is founder and managing partner of Tritium Partners, a $1.5 billion private equity firm, and has spent more than 25 years building and investing in companies. His experience includes early involvement with Newgistics, HomeAway, RetailMeNot, Vida Capital, RVShare, and Giact Systems. Previously a managing partner at Austin Ventures and partner at Boston Consulting Group, Phil brings an investor’s pattern recognition to the decisions entrepreneurs make about growth, capital, and scale.

Jamie Mathews

Entrepreneur | Investor | Community Builder

Jamie has spent more than two decades building businesses, real estate, and community-focused organizations. His work includes real estate investments across Texas, Colorado, and California, founding Austin’s Pond Hockey Club, and co-founding the Tecumseh Foundation. Part of the Acton community since 2004, Jamie brings a long-term builder’s perspective to entrepreneurship: creating ventures that endure, serve people, and become meaningful institutions.

Cory Older

Co-Founder ESA | Entrepreneur | Real Estate Developer | Acton MBA

Cory co-founded River City Capital Partners, where he has secured more than $500 million in project funding and led the development of multifamily, mixed-use, and land projects across Central Texas. Previously with Deloitte and Keller Williams Realty International, he is a CPA and Acton MBA graduate. Cory brings the builder’s combination of financial discipline and execution: underwriting risk, raising capital, making decisions, and carrying a project through to completion.

Hugo Díaz

Co-Founder ESA | Entrepreneur | Investor | Director, Acton MBA Guatemala

Hugo has spent more than two decades launching and scaling companies across countries and industries, including ventures that have served millions of customers. His experience includes building and exiting a company through acquisition, and he now serves as director of Acton MBA in Guatemala and an investor on Shark Tank Guatemala. Hugo brings a global founder’s perspective shaped by building across borders, sectors, and stages of growth.