David Swensen, chief investment officer of Yale University’s endowment fund, is concerned that low market volatility could lead to another market crash, according to a recent Bloomberg article.

During his remarks at the Council on Foreign Relations in New York earlier this month, Swensen said, “When you compare the fundamental risks that we see all around the globe with the lack of volatility in our securities markets, it’s profoundly troubling.”

According to the article, Swensen’s investment strategy of shifting away from U.S. stocks to alternative investments (including private equity) has been widely copied and has generated billions for the university (bringing total assets to a record $27.2 billion as of midyear). However, the CIO said he has warned university officials that returns for the school’s endowment—which have averaged 13.5% per year during his 32-year tenure—could be much lower going forward, to the tune of 5% per year.

During his talk, Swensen expressed concern about valuations more than economic factors. He asserted, “We have to take strategic positions in the portfolio,” and focus on the percentage of the portfolio in uncorrelated assets. “Those are the assets,” he argued, “that would protect the endowment in the event of a market crisis.”