About

Bonsai Partners was created out of a belief that active management, when approached with deliberate thought and care, can put investors in the best position to succeed.

We pursue this ideal by maintaining a highly concentrated portfolio of unusual public equity investments, structured on honest terms for our partners and guided by a long-term mindset.

Our mandate is deliberately broad. We place no limits on sectors, geographies, or company sizes because we cannot know in advance where the most compelling opportunities will appear, or how we will evolve as investors.

Our constraints instead revolve around whether we understand the business, trust its leaders, align with the company’s objectives and values, and find the investment price acceptable.

Andrew Rosenblum
Managing Partner

Andrew Rosenblum founded Bonsai Partners in 2018. Previously, he was an investment professional at Matrix Capital Management, LP, and later joined Adaptive Biotechnologies, contributing to their cancer immunotherapy business. Andrew graduated from the Ross School of Business at the University of Michigan in 2010 and lives in San Diego with his wife and two daughters.

Nico Kirsten
CFO

Nico joined Bonsai Partners in 2025, bringing more than two decades of experience in fund accounting and finance. Prior to Bonsai, he spent thirteen years with StepStone Group, a global private markets firm. Nico began his career with PwC in his native South Africa, later rejoining the firm in Dallas, where he audited a variety of alternative investment funds. A licensed CPA, Nico lives in San Diego with his wife and their four daughters.