Harvard University’s endowment, which stood at $36.9-billion on June 30, has lost at least $8-billion in the four months since then, the university’s president says.

In a letter on Tuesday to Harvard’s deans, Drew Gilpin Faust said that Harvard’s endowment had lost at least 22 percent of its value since June 30 and had very likely lost more.

Harvard is preparing for a scenario in which the endowment, the largest of any university, is down 30 percent for the year, the letter said. Harvard, which takes 35 percent of its operating budget from investment income from the endowment, will need to reduce its overall spending to account for those losses.

Ms. Faust and Edward C. Forst, the university’s executive vice president, said they expected Harvard would spend a higher percentage of its endowment than in years past.

Mr. Forst told The Harvard Crimson that university leaders had delayed setting the payout rate for the next fiscal year until the university’s schools could re-evaluate their budgets. The rate for the next year is typically announced in December.

“Given the extreme volatility in the markets, I don’t expect [the payout rate] will be set until we have a much more concrete sense about financial plans and endowment performance,” Mr. Forst said. —Kathryn Masterson