The Endowment Model and Modern Portfolio Theory

We develop a dynamic portfolio-choice model with illiquid alternative assets to analyze conditions under which the “Endowment Model,” used by some large institutional investors such as university endowments, does or does not work. The alternative asset has a lock-up, but can be voluntarily liquidated at any time at a cost. Quantitatively, our model's results match the average level and cross-sectional variation of university endowment funds' spending and asset allocation decisions. We show that asset allocations and spending crucially depend on the alternative asset's expected excess return, risk unspanned by public equity, and investors' preferences for inter-temporal spending smoothing. Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.