On January 30th, 2019 VXZ will be discontinued. It is being replaced by VXZB. In addition to VXZ being delisted, VXX will also be delisted and replaced by VXXB. So, any of you using VXZ (like I am) will want to replace the position with VXZB before the end of next month. You can read more about it at Six Figure Investing.