Quote from deviltrader:
I can think of many scenarios where the PM haircut does not converge to Reg-T. Are you suggesting it always does?
Yup, the only scenarios are locks and boxes (arbitrage). In other words, conversions and reversals that carry no risk. Any position that does not fall into that category converges. I'm always open to people proving me wrong. Lay out a trade and we'll prove it mathematically. Also, please take equity into your equation. In other words, If I buy 100 straddles in a PMA account and JBO, my margin will be 50% higher in a PMA account (37.50 per contract vs 25.00) but our equity will be dropping the same through theta. These positions also converge through equity depletion.
