A diagonal in the first part, yes. However in the second part this poster clearly states that they have scalped SPX calendar spreads too, filling orders for 0 or a net credit. So therefore yes it absolutely can be done. Just Tastytrade don't want their customers doing this. For some very strange reason.
And I'm the king of England. I've filled SN calendars at zero outlay into the earnings vol-switch. So what? We're talking about index here and all you've shown is some fool shorting gamma in diagonals. The difference between your bear call spread and the box is the put spread. There is a reason it's trading 0 x 5. Look at the 15% ITM call spread today and 1) zero volume and 2) zero var.
What is their motivation? By putting you on liq-only they lose exercise fees and commissions. It's in the best interest to nickel you until you're gone. They are acting ethically here by saving you from yourself. By selling the deep cs you are BUYING the deep OTM ps. There is no advantage to the 100-credit v the 0 debit in the ps. Sure, it's an arb (less fees) but it won't trade unless we crash on any given day. You're going to spend $5/day + commissions + fees to sell a cs in the 10-15% of cases near the end of the day when someone wants to use your stupidity to buy themselves a Happy Meal. TT is a buck all in. So you're paying $5 + $2 commissions + $5 to exercise as you will not be able to fill even at a nickel. You won't see it trade to 99.9 even if we trade 5% lower. All you're accomplishing is getting picked off late in the day (if you fill) and sending endless messaging through TT's front end. Stop or self-immolate (or both).
%% No vegetables is bad for you . If that confuses you about working 40 years for a gold watch exit/then dont do it LOL I dont do that, but to each his or her own
"Interactive Brokers also has some arbitrary rule whereby establishing a position cannot exceed your account equity multiplied by 30." Can anyone explain this rule with a couple of actual examples that cover different scenarios?