The separation of sister chromatids occurs during anaphase, which is one of the phases of mitosis. During anaphase, the spindle fibers attached to the kinetochores of the sister chromatids shorten, pulling the sisters apart toward opposite poles of the cell. This ensures that each new daughter cell will receive an identical set of chromosomes. After anaphase, the cell progresses into telophase, where the chromosomes reach the poles, and the cell prepares to divide into two.
