To many of his peers at other universities and on Wall Street, Yale Chief Investment Officer David Swensen can do no wrong. Under the investment guru’s leadership, after all, Yale’s endowment grew by an average of 16.8 percent every year for two decades — until last year, when it lost 24.6 percent. That tumble has led the blog 24/7 Wall St. to call the Yale endowment, along with those of Harvard and Duke, the “worst managed endowments” for the fiscal year ending June 30, 2009.

Using a survey of 842 educational endowments released last week, the blog says it compared schools based on absolute and percentage losses, focusing on institutions worth over $1 billion that lost at least five percent more than the average endowment in the survey. On average, the endowments in the study lost 18.7 percent last year. Though only 33 endowments of the 842 studied actually grew in value, 24/7 Wall St. singled Harvard, Yale and Duke out for their endowments’ particularly poor performance.

But at least Yale wasn’t the worst: the blog gave that honor to Harvard for losing the most in absolute dollars and among the most in percentage points, noting, “This is particularly ironic because Harvard promoted the brilliance of the people who ran its fund to both alumni and the press.” (Of course, the person who currently runs Harvard Management Co. is a Yalie, Jane Mendillo ’80 SOM ’84.)

But a statement from the Commonfund InstitutProxy-Connection, which co-authored the survey, seems to contradict the blog’s insistence that these endowments are badly managed because they lost billions of dollars in the economic downturn. “The top decile performers in this exceptional year achieved their investments results by following highly unorthodox strategies that are unlikely to be repeatable, much less prove successful over the long term,” John Griswold, the Commonfund Institute’s president, said in a release accompanying the survey last week.

The list of best-managed endowments, meanwhile, was topped by Washington State University (down nine percent), Virginia Tech (down 14 percent) and the University of Utah (also down 14 percent).