How Volatility ETPs Really Work TL;DR
The short-term Volatility ETPs hold a mix of the two nearest-to-expiration VIX futures. The ETPs are either long both of those (e.g., VXX, UVXY, UVIX, VIXY) or short both of those (SVIX, SVXY). If the VIX futures term structure is in contango, with prices increasing with time, then the tendency will be for both futures to drop in value on a daily basis–so a long ETP …
