Given a Lebesgue integrable function f over [0, 2π], we consider the sequence of matrices {Y n T n [f ]} n , where T n [f ] is the n-by-n Toeplitz matrix generated by f and Y n is the flip permutation matrix, also called the anti-identity matrix. Because of the unitary character of Y n , the singular values of T n [f ] and Y n T n [f ] coincide. However, the eigenvalues are affected substantially by the action of the matrix Y n . Under the assumption that the Fourier coefficients are real, we prove that {Y n T n [f ]} n is distributed in the eigenvalue sense aswith g(θ) = |f (θ)|. We also consider the preconditioning introduced by Pestana and Wathen and, by using the same arguments, we prove that the preconditioned sequence is distributed in the eigenvalue sense as φ 1 , under the mild assumption that f is sparsely vanishing. We emphasize that the mathematical tools introduced in this setting have a general character and in fact can be potentially used in different contexts. A number of numerical experiments are provided and critically discussed.