Chief Investment Officer David Swensen has been diagnosed with cancer, according to students in his economics seminar.

Swensen, who is responsible for managing the University’s roughly $19 billion endowment, did not attend this Monday’s session of “Investment Analysis,” which he teaches with Investments Office Senior Director Dean Takahashi, five students in the course said. At that meeting, Takahashi informed the class that Swensen has been diagnosed with cancer and will be absent from the course for about one month due to medical reasons, those students said. None of them knew the type of cancer with which Swensen has been diagnosed, or any other information about his prognosis.

Neither Swensen nor Takahashi could be reached for comment Wednesday night. University spokesman Tom Conroy declined to comment on whether Swensen has been diagnosed with cancer, and whether he will be able to continue his responsibilities as chief investment officer over the next month. University President Richard Levin also declined to comment.

Swensen arrived at Yale in 1985 after spending six years on Wall Street, and is widely credited with redefining the model for institutional investing — pioneering a nontraditional investment strategy that favors illiquid, alternative assets and takes a long-term view. The strategy, often termed the “Yale Model,” propelled the University to investment returns of near or above 20 percent between 2004 and 2007, and has been adopted by many of Yale’s peers.

“What David has figured out extremely well is what are the integral parts of a very sound investment process,” Anthony Knerr ’60 GRD ’64, the founder and director of a consulting firm for nonprofits, told the News in 2009. “Wouldn’t it be terrific if every American college had a David Swensen? But alas, that’s not the case.”

Yale’s endowment has grown dramatically during Swensen’s 27-year tenure, from just over $1 billion when he arrived to $19.4 billion as of June 30, 2011. The endowment lost almost a quarter of its value in fiscal year 2009, following the onset of the nationwide economic recession, but has since rebounded and returned 21.9 percent in fiscal year 2011.

Debra Zumwalt, vice president and general counsel at Stanford University, said she does not think that high-level university administrators are required to disclose serious health conditions. The issue is less relevant in higher education than in the corporate world, where executives are in charge of publicly traded companies, she said.

Swensen earned a Ph.D. in economics from Yale in 1980.

Tapley Stephenson contributed reporting.