Convexity Investments

David Kostin serves as founder, principal, and chief investment officer. He is the sole named decision-maker per public record. Kostin's background as Goldman Sachs' US equity strategist for roughly 20 years provides the analytical backbone for the office's macro-driven posture.

Convexity operates as a single-family office managing capital generated by David Kostin's career. There is no public record of the firm managing outside capital or registering as an RIA. The firm's strategy and deal flow, including the 2017 vehicle with HCI Equity Partners, reflect proprietary family capital deployment.

Convexity employs a hybrid model. The office has acted as an LP in external funds — such as the structured credit vehicle anchored with HCI Equity Partners in 2017 — while also pursuing direct co-investments in private credit and real assets like renewable energy infrastructure. The mix is sized through a top-down macro risk overlay.

The office focuses on hedge fund allocations, private credit, and US energy-transition real assets, including community solar and battery storage projects. The mandate is opportunistic within those verticals but explicitly anchored to macro-thematic conditions rather than a fixed sector-agnostic growth strategy.

The wealth originates from David Kostin's tenure as Goldman Sachs' chief US equity strategist, a senior position he held starting in 2004 (per Bloomberg, 2014). The family office was seeded with compensation amassed over a 20-year career at the bank.

Convexity has historically engaged in co-investment structures when partnering with specialist managers in credit. The 2017 structured-credit vehicle with HCI Equity Partners is the most visible example, suggesting the office pools its capital alongside experienced originators to access lower-middle-market deal flow rather than bidding alone.

Kostin's office sizes illiquid allocations using a forecasting framework rooted in his equity-strategy methodology. During periods of elevated macro uncertainty, the office tends to reduce commitment pace in real assets while increasing short-duration credit or hedge fund allocations that offer quicker liquidity — a discipline more typical of a pension fund than a family office.