The endowment had a return of 4.8% over the last fiscal year, while trustees are usually asked to approve endowment spending between 4.5% and 5.5%.
https://annualreport.uchicago.edu/page/endowment
With spending at 5.5%, the endowment’s return was slightly below the break-even point. It went down by just over $100 million as a result.
https://annualreport.uchicago.edu/page/financial-results-fiscal-year-2015
The chart on the right (second link) shows just over $6 billion in total liabilities, of which $4.2 billion consists of bonds/notes.
In the near term, the endowment is likely to decrease slightly in real terms. In the longer term, if the capital campaign comes anywhere close to its $4.5 billion goal, the endowment will increase further. Sooner or later, the debt will be paid down, when interest rates are no longer at a historic low and there’s less of an incentive to borrow more.