The Perpetuity Trap: Why Foundation Endowments Misallocate Capital

The perpetual foundation — an endowment designed to exist indefinitely while distributing only a small fraction of its corpus each year — is treated as the default architecture of institutional philanthropy, a neutral container for serious charitable intent. This paper argues that perpetuity is not a neutral container but a capital structure with its own logic, and that this logic is systematically misaligned with the missions it is meant to serve. The misalignment is structural rather than behavioural: a foundation operating a perpetual endowment is bound by two fiduciary duties — to preserve the corpus and to advance the mission — and the real-terms preservation mandate forces the first to dominate the second, so the institution is optimised for its own survival rather than for resolution of the problem. Three failure modes follow: corpus primacy, in which preservation is the binding constraint and the mission the residual; the payout floor as anchor, in which a regulatory minimum designed to constrain the worst behaviour anchors the typical behaviour; and horizon inversion, in which the structure holds capital longest precisely where early deployment returns most. The paper shows why the sector's three standard reforms — higher payout, mission-related investment, spend-down — cannot reach the conflict, and states the conditions an aligned alternative would have to satisfy.