Just another example of weird stuff. UVXY is supposed to move 2x the direction of the VIX, SVXY 1x the inverse of the VIX. So the SVXY move today, looks like it might be reasonable. But why is UVXY also up so much? If it holds the positions it says it does shouldn't it be down big?
You need to look at what the holdings are. SVXY is all about contango/backwardation, nothing to do with VIX spot. It is about VIX future curve.