There is strong empirical evidence that the pricing kernel is Ushaped,which provides a way to explain the substantial coskewnesspremium. Existing studies typically use a polynomial approximationof the pricing kernel. Problematically, these polynomials have, inmost cases, increasing parts by...

Many statistical applications require an estimate of a covariance matrix and/or its inverse.When the matrix dimension is large compared to the sample size, which happensfrequently, the sample covariance matrix is known to perform poorly and may suffer fromill-conditioning. There already exists...