The present invention provides a method for preparation of a high concentration liquid formulation (HCLF) of an antibody or a fragment thereof. The present invention also relates to a method for stabilizing an anti-CD20 antibody or a fragment thereof in a liquid pharmaceutical formulation. Furthermore, the present invention relates to a liquid pharmaceutical formulation of a veltuzumab antibody or a fragment thereof comprising at least 155 mg/mL of a veltuzumab antibody or a fragment thereof.