If you are scared or not willing to lose at all, don't even try this. Alos, timing is key; If you don't know when to get in, you may end up a loser or you will always finish ITM
I think piccon has responded to your concern, and i just explain why I made the trade myself. I don't have any CTM vertical. I have a combo with many long calls at different strikes and different expiration. In short, these CTM short calls are protected by many long calls (like a diagonal). You cannot look at one trade to declare if it is risky or not. Look at market makers, they short a lot of ITM, ATM and CTM options, but these are hedged by other means (other long options, or the underlying). I manage the whole book using my own method. Perhaps Mark can give us insights on how market makers make money by managing their books.
I think those sources must be from a similar feed. The spike does not show up on Bloomberg. Bad data.
To take advantage of the low IV today (rvx at 17 at trading time) bto rut jun 900 call x 6 @3.7 sto rut dec 800 call x 2 @ 6.6