We study the optimal portfolio selection problem with transaction costs. In
general, the efficient frontier can be determined by solving a parametric
non-quadratic programming problem. In a general setting, the transaction co
st is a V-shaped function of difference between the existing and the new po
rtfolio. We show how to transform this problem into a quadratic programming
model. Hence a linear programming algorithm is applicable by establishing
a linear approximation on the utility function of return and variance.