The minimisation of the return variance is one of the classical topics of portfolio theory. One of the main difficulties of variance minimisation is the neccessary input factors- variances and covariances- of the assets of the investment universe- are unknown. Often these variances and...

We develop a shrinkage theory based framework for determining optimal port-folio weight constraints for minimum-variance portfolios in presence of parameteruncertainty. We propose to impose the set of constraints that yields the opti-mal trade-o between sampling error reduction and bias for the...

Expected returns can hardly be estimated from time series data. Therefore, many recent papers suggest investing in the global minimum variance portfolio. The weights of this portfolio are usually estimated by replacing the true return covariance matrix by its time series estimator. However,...

This paper presents a new approach to incorporate estimation risk into mean-variance portfolio selection. The key contribution of our analysis is that we model the estimation risk as a second, independent source of risk.