Performance Analysis of Tyler's Covariance Estimator
  This paper analyzes the performance of Tyler's M-estimator of the scatter matrix in elliptical populations. We focus on the non-asymptotic setting and derive the estimation error bounds depending on the number of samples n and the dimension p. We show that under quite mild conditions the squared Frobenius norm of the error of the inverse estimator decays like p^2/n with high probability. 
Ilya Soloveychik and Ami Wiesel
math.ST stat.TH