ProShares, the ETF management company behind SVXY and UVXY, has altered the daily tracking goals of these two ETFs. SVXY now seeks to track only 0.5x the inverse of the daily move in VIX, down from 1.0x the inverse of the daily move in VIX.
UVXY now seeks to track 1.5x of the daily move in VIX, down from 2.0x.
This is an unexpected, but not completely surprising change, in light of the short volatility trade collapse in early February 2018. While it's too early to forecast how these changes will affect SVXY's stock price, it's very likely that SVXY will no longer be the high flyer it used to be. UVXY's change is not as drastic, and should still track towards $0 over time.
I've been collecting the daily portfolio for SVXY as well as for VMIN, another inverse VIX ETF. I hope to provide a full write-up that will reflect these changes in these funds' portfolios.
For more information, here's a link to the ProShares press release: http://www.proshares.com/news/proshare_capital_management_llc_plans_to_reduce_target_exposure_on_two_etfs.html
Disclosure: I am/we are long VMIN.
Additional disclosure: I am also long SVXY puts and calls, VMIN calls, VIX puts.