Jim MacDonald

Jim joined Yellowstone as Chief Executive Officer in September 2025, bringing more than 25 years of leadership experience including senior executive positions at Juno Therapeutics and Sana Biotechnology.

Previously, Jim was Co-Founder and Executive Vice President & General Counsel at Sana Biotechnology, where he played a key role in building and scaling the business and guiding the company's private financings and Nasdaq IPO. Earlier, he served as Senior Vice President and Chief Intellectual Property Officer at Juno Therapeutics, contributing to the company's growth through to its acquisition by Celgene/BMS.

He holds a J.D. from Vanderbilt University Law School and a B.S. in Chemical Engineering from Stanford University.