Many rutile-type materials are characterized by a shear softness under pressure, which is coupled to a Raman-active librational motion. Upon complete softening of the shear elastic constant, these materials adopt the CaCl₂ structure. Using extended x-ray absorption fine structure spectroscopy (EXAFS), x-ray diffraction (XRD) and Raman spectroscopy, we have observed a disordered regime in rutile-type SnO₂ at pressures between 5-10 GPa , in which four-probe electrical resistance experiments measure an anomalous increase in conductivity up to 4 orders of magnitude (i.e. a drop in the band gap, E_g, up to 0.47 eV). Ab initio calculations reveal that decrease in E_g may only be explained by the displacement of single anions, which results directly from the softening of the librational mode under pressure, and we propose that the same behavior should be a feature across all materials exhibiting a rutile®CaCl₂ transition.