I would have thought you are correct. Harvard is sitting on $32B and Stanford $18.7B in tax-free endowments, the largest and 3rd largest endowments respectively.

However, Yale is on the list and they have $20.7B (2nd largest). It does seem disingenuous for Yale to claim "[t]he prospect of substantially increased financial risk would discourage universities and other patent holders lacking extensive litigation resources from legitimately defending their patents." Not a whole lot of businesses are sitting on +$20B in cash period, much less +$20B tax free.

As a side the top 10 school endowments in 2013 = ~$141B.[1]

[1] http://www.usnews.com/education/best-colleges/the-short-list...

Ding ding ding!