Jason
Birnbaum

Founder, Managing Partner
NMLS#487223

Jason is Co-Chief Executive Officer of Graintree, where he oversees offtake and capital partnerships, professional lending origination, financial operations, and firmwide strategy. He brings extensive leadership experience building and scaling complex lending platforms, with a career focused on strategic growth, disciplined execution, and team development.

Most recently, Jason served as President of Flagstar Private Bank, where he led private bank strategy and oversaw all private client banking groups. Prior to Flagstar, he was Senior Managing Director at First Republic Bank, where he co-created and launched the Professional Loan Program, now an industry-leading product for private equity professionals. 

Over the course of his career, Jason has originated and managed several billion dollars in mortgage loans, unsecured lines of credit, and business lending, while overseeing private equity, operating, capital call, and personal liquidity credit relationships. He has built and led high-performing teams and mentored many relationship managers and lenders.

Jason studied economics at New York University and Interdisciplinary Studies at Towson University. He lives on Long Island with his family and is actively involved in coaching and leading youth sports programs in his community.