FAZ did not go up 3X amount of the inverse of ^RIFIN.
RIFIN closed 2.33 percent down; so FAZ should have closed 6.99 percent up (2.33x3=6.99). Instead FAZ only went up 5.54 percent. That is a huge difference when you are trading options on expiration date. I am going to start keeping track on how far off this 3X inverse ETF is each day. I will keep everyone updated.
I've calculated the "expected" FAZ with the actual FAZ since the March low. Short-term it is off, but long term it is not. It's only about 20 cents off, as of last week. Open a big spreadsheet, get historical values of RIFIN and FAZ, see for yourself.