University of Pennsylvania's endowment returned 17.5% for the fiscal year ended June 30, said Ronald Ozio, a spokesman for the Philadelphia-based school.
Endowment assets totaled $9.6 billion as of June 30, up 23% from the year before.
Strong investment performance in private and public equities drove the growth in Penn's endowment, figures from the university show.
For the three years ended June 30, the endowment returned an annualized 10.9%, and for the 10 years, 8%.
The growth in the endowment for the fiscal year reflects investment gains of $1.4 billion, a spending rule distribution of $306 million, new gifts of $186 million and net transfers into the endowment, including the reclassification of certain investment assets.