It is desirable but nontrivial to obtain a portfolio that enjoys both sparsity and optimality. We propose a portfolio model that is rooted in the mean-variance framework, incorporating the 80 constraint as a precise r...
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It is desirable but nontrivial to obtain a portfolio that enjoys both sparsity and optimality. We propose a portfolio model that is rooted in the mean-variance framework, incorporating the 80 constraint as a precise restriction to ensure a sparse portfolio comprising no more than a specified number of assets. Moreover, the simplex constraint is also imposed to ensure the feasibility of portfolio. This model is difficult to solve due to the nonconvexity of the 80 constraint and the geometric complexity of the intersection of the two constraints. To address this issue, we establish the equivalence relation between a local optimum of a general 80-constrained problem and a global optimum on a restricted set of variables. Based on this result, we develop a two-stage accelerated forward-backward algorithm that converges to a locally optimal solution to the proposed autonomous sparse Markowitz portfolio model, with an o(1/k2) convergence rate in terms of function value. Extensive experiments on 7 benchmark data sets from real-world financial markets show that the proposed method achieves state-of-the-art performance in various evaluating metrics.
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