Propeller

Brian Halligan co-founded HubSpot in 2006 and built it into a company that, by the time of his retirement as CEO in 2021, had defined an entire category of enterprise software. What he built next is, by almost any measure, more unusual. Propeller — a venture capital fund focused exclusively on the ocean-climate nexus — was launched in Cambridge, Massachusetts in 2022 with a thesis that is both simple and radical: that the ocean, covering more than 70 percent of the planet's surface and absorbing approximately 30 percent of human-generated carbon dioxide, is the largest and most underutilized tool available for addressing climate change, and that the companies building at that intersection represent one of the most asymmetric investment opportunities of the next decade.

Halligan co-founded Propeller with partner Devdutt Yellurkar, and the firm has since added Managing Partner Rodrigo Prudencio, previously the co-founder and leader of Amazon's Climate Pledge Fund, and a team of investment professionals with backgrounds in climate science, marine biology, and ocean engineering. The firm closed its inaugural $117 million fund in early 2024 — backed by high-net-worth individuals, family offices, and strategic and institutional capital — and invested in 14 portfolio companies spanning the three verticals it helped define for the sector: Ocean Carbon (companies removing CO2 from seawater and the atmosphere), Ocean Industrials (sustainable aquaculture, food systems, and materials), and Ocean Organics (blue biotechnology and natural marine compounds).

Propeller's formal partnership with Woods Hole Oceanographic Institution gives it direct access to scientists and intellectual property while supporting a defined technology-transfer process that spins out startups with scientists as founders — the kind of structural innovation that has allowed the firm to be present at the formation of companies that would not otherwise have had a clear path to commercial development. The firm refuses capital from oil companies, a policy that reflects both its values and its understanding of what LP alignment means in a climate-focused fund. That J.P. Morgan now uses the three-vertical framework Propeller helped establish to define the blue-tech investment landscape is a form of market validation that arrived faster than most first-time fund managers experience it.