A financial endowment is a legal structure for managing, and in many cases indefinitely perpetuating, a pool of financial, real estate, or other investments for a specific purpose according to the will of its founders and donors. Endowments are often structured so that the inflation-adjusted principal or "corpus" value is kept intact, while a portion of the fund can be (and in some cases must be) spent each year, utilizing a prudent spending policy.

Endowments are often governed and managed either as a nonprofit corporation, a charitable foundation, or a private foundation that, while serving a good cause, might not qualify as a public charity. In some jurisdictions, it is common for endowed funds to be established as a trust independent of the organizations and the causes the endowment is meant to serve. Institutions that commonly manage endowments include academic institutions (e.g., colleges, universities, and private schools); cultural institutions (e.g., museums, libraries, and theaters); service organizations (e.g., hospitals, retirement homes; the Red Cross); and religious organizations (e.g., churches, synagogues, mosques).

Private endowments are some of the wealthiest entities in the world, notably private higher education endowments. Harvard University's endowment (valued at $53.2 billion as of June 2021) is the largest academic endowment in the world. The Bill and Melinda Gates Foundation is one of the wealthiest private foundations as of 2019 with endowment of $46.8 billion as of December 31, 2018.