This paper shows that donors that maximize relative aid impact spread their budgets across many recipient countries in a unique Nash equilibrium, explaining aid fragmentation. This equilibrium may be inefficient even without fixed costs, and the inefficiency increases in the equality of donors'...

Some multilateral agencies implement aid projects in a broad range of sectors, with aid disbursements showing a strong overlap with those of bilateral donors. The question then arises of why do bilateral donors delegate sizable shares of their aid to non-specialized agencies for implementation?...