  We have performed pressure dependent X-ray diffraction and resonant X-ray
emission spectroscopy experiments on USb$_2$ to further characterize the AFM-FM
transition occurring near 8 GPa. We have found the magnetic transition
coincides with a tetragonal to orthorhombic transition resulting in a 17%
volume collapse as well as a transient $\textit{f}$-occupation enhancement.
Compared to UAs$_2$ and UAsS, USb$_2$ shows a reduced bulk modulus and
transition pressure and an increased volume collapse at the structural
transition. Except for an enhancement across the transition region, the
$\textit{f}$-occupancy decreases steadily from 1.96 to 1.75.
