Major mergers distributions, the top two rows are loose group galaxies and the bottom two rows are field galaxies, a convention that is followed throughout this work. The magnitude of the merger is represented by the virial mass of the host halo divided by the virial mass of the merging body. As stated in the text, mass ratios are calculated at the time the haloes first come into contact as the mass associated with merging structures is often greatly diminished by the time the disk is disrupted. The majority of mergers take place at early times when the galaxy halo still has a low mass and assembly is mostly hierarchical. We find that only mergers shown above to occur further back than 4 Gyr have any significant influence on the disk structure and that mergers can take several Gyr before they have descended far enough into the halo to disrupt the disk. A dashed line shows the lower bound of the commonly used definition of major mergers.