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Robert Israel

Co-Founder & Managing Partner

Robert brings vast experiences in operating businesses and achieving efficiency. He is currently on the board of Ogre Logistics, providing guidance and strategic directions to the CEO and management team. He invested in Keg Logistics and grew the company’s value 30 times over the course of 3 years. While developing the business, Robert led the merger of Keg Logistics and Atlas Keg Company. The synergy created through the transaction was highly accretive, which led to another dealing with Seaport Capital a year later.


Clayton Mobley

Co-Founder & Managing Partner

Clayton is a proven executive who achieved early success with a large multi-national industrial company before founding Spartan Value Investors. The Spartan family now consists of six different entities and seven brands, providing exceptional returns with low volatility. Clayton applied the same focused intensity to launching Green Rock in 2017. Clayton created sustainable investment programs at Green Rock that align investors’ best interests with that of the company while maintaining disciplined standards to preserving capital. Throughout his entire experience, Clayton has built four businesses with Total Enterprise Value exceeding $260 million. He also hired and developed four CEOs and eight senior executives.


Dan Nguyen



Dan provides a wealth of experience in investment banking and private equity investing. He has been involved with many transactions during his career, including sell-side M&A, IPO, and acquisition financing. Dan has an MBA from the Wharton School at the University of Pennsylvania and a Bachelor of Science from Brigham Young University.


Bill Nabors



With C-suite experience as the financial and operational lead of multiple businesses, Bill focuses on connecting the day-to-day of portfolio companies with the long-term financial goals of Abacus.


Dan Nguyen


205-661-8189 ext. 704

Dan provides a wealth of experience in investment banking and private equity investing. He has been involved with many transactions during his career, including sell-side M&A, IPO, and acquisition financing. In addition, Dan has a passion for healthcare investing and an appreciation for the healthcare system's complexities. His wife is a pharmacist, and his brother currently attends medical school to be an anesthesiologist. Dan has an MBA from the Wharton School at the University of Pennsylvania and a Bachelor of Science from Brigham Young University.


Bill Nabors


205-661-8189 ext. 701

As COO for, Bill's operational and financial expertise caught the eye of Green Rock where he became the interim CFO for a portfolio company in the mining industry. After restructuring their balance sheet and stabilizing cash flow, he was charged with deploying Green Rock Fund I ($7 million) and Fund II ($23 million). Bill is an expert in underwriting credit transactions for small and medium businesses. Bill has a Bachelor's degree from Samford University.


Chris Devine



Chris is an accomplished business leader, having held top management and executive level positions with several organizations. Chris began his career as an engineer before moving into management for an international manufacturing company. He later became the COO and then CEO of a large sponsor company offering investment programs with a focus on sustainable development. He currently is a partner at Abacus Investments and a founder at Denali Capital. Through these extensive career experiences, Chris offers a unique perspective on investments to maximize value. Chris holds an MBA from the University of Alabama – Birmingham and a BS in Industrial Engineering from Purdue University. 


Yash Tiwari



Yash has a wealth of experience in investing, real estate, and financial markets. He has previously worked on generating financial research for IPO and M&A transactions. Yash has a Masters degree from Yale SOM with a focus in Asset Management.



Nathan Hertzog

 General Counsel


Nathan manages legal matters for Abacus and its portfolio companies. Nathan is instrumental with deal structuring, negotiation, legal due diligence and transaction execution. He is a resource to our portfolio company management teams on corporate, commercial and regulatory matters. Prior to joining Abacus, Nathan spent eight years in private law practice representing private fund clients on mergers and acquisitions and venture capital investments and advising founders on entity formation, seed and growth capital raises, exit transactions, incentive strategy, dispute resolution and general corporate needs. Nathan received his JD from Boston University School of Law and his AB/MPA from the University of Georgia. He is licensed to practice law in Tennessee.


Chris Guest

 Operations Executive


Over the past 17 years of his career, Chris has held numerous operational leadership roles across a variety of industries. From 2008 to 2020, he served as Chief Operations Officer for a portfolio of companies in the telecommunications industry, while also driving growth for the family office through strategic investments and acquisitions. Prior to that, he worked in several Engineering and Operations Management positions at United Parcel Service. His strengths and experiences in long-term strategy development, converting strategy into execution, and driving operational excellence fit perfectly into the Abacus investment philosophy. Chris holds a BS and MS in Industrial Engineering from the University of Alabama and remains active in several national engineering societies.


Carson has over 10 years of experience in accounting, finance, and consulting. He was previously with Baker Tilly Virchow Krause, a leading public accounting firm, where he managed the financial statement attestation process for both public and non-public clients, as well as assisted certain clients throughout their mergers, acquisitions, and due diligence activities.


Luke Leeth



Luke joined the Abacus team during 2021, after an approximate six year stint in public accounting at a large national firm performing assurance services. He brings a wealth of knowledge in the areas of external and internal financial reporting, accounting for business combinations and complex transactions, as well as establishing internal controls over business cycles. Luke has a passion for healthcare companies and experience servicing entities across the continuum of care, and enjoys the complexities of the revenue cycle and reimbursement models that are so unique to this industry. Luke is a certified public accountant, and has a Bachelors degree and Masters degree in accounting from Samford University.

Carson Huff




Sarah Stinebaugh

 Executive Assistant


Sarah joined the Abacus team in August 2021. She has served in a variety of roles, ranging from support to leadership, for organizations in both the non-profit and investment banking industries. At Abacus, Sarah manages executive scheduling and ensures that day to day operations run smoothly. Sarah received her BA and MBA from the University of Alabama at Birmingham.



Larry Anderson, MD

Dr. Anderson, a dermatologist for over 30 years, established and led one of the first private practices in the nation to scale, growing to become the largest single-specialty practice in Texas. He partnered with private equity in 2012, serving on the board and as Chief Medical Officer for eight years, helping develop one of the largest dermatology companies in the country. Dr. Anderson has broad experience in strategic/tactical planning, integration, technology, operational effectiveness, and efficiency while focusing on clinical excellence, a positive corporate culture, and patient/employee satisfaction. His experience with small and large groups, including private equity, enables him to help build successful medical organizations. 


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