Snowmass benchmark points and three-loop running

We present the full three-loop β-functions for the MSSM generalised to include additional matter multiplets in 5, 10 representations of SU (5). We analyse the effect of three-loop running on the sparticle spectrum for the MSSM Snowmass benchmark points. We also consider the effect on these spectra of additional matter multiplets (the semi-perturbative unification scenario).