Mar\v{c}enko-Pastur Law for Kendall's Tau
  We prove that Kendall's Rank correlation matrix converges to the Mar\v{c}enko-Pastur law, under the assumption that the observations are i.i.d random vectors $X_1$, $\dots$, $X_n$ with components that are independent and absolutely continuous with respect to the Lebesgue measure. This is the first result on the empirical spectral distribution of a multivariate $U$-statistic. 
Afonso S. Bandeira, Asad Lodhia, and Philippe Rigollet
math.ST math.PR stat.TH