Critics of the aid industry have accused it of acting like a cartel (Easterly 2002). The accusation has some bite-globally the industry remains somewhat concentrated, and for the typical recipient country, highly concentrated. Yet the most striking fact about the industry is how relentlessly...

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'...