My account is almost at the point where it can have portfolio margin, so I want to make sure I understand it properly before using it. As I understand it now, Reg T evaluates each position individually and simply sums the margin requirements. Portfolio Margin, however, evaluates the portfolio as a whole (as the name implies). This means that all options on an underlying are evaluated together instead of separately. Am I correct also that stocks with strong correlations are also evaluated together? That may be a stretch, but just asking, and based on what metrics? Simple historical correlation? Also, long options in a Reg T cannot be used as collateral, but they can in Portfolio Margin? Does this mean that a Poor Man's Covered Call has different margin requirements under Reg T vs. Portfolio? Right now if I buy a LEAP and sell a short-term call, the long call counts against my liquidity and the short-term call counts against my margin, but under Portfolio Margin, the short-call should count significantly less against my margin because of my hedged exposure with the LEAP?
PMA is risk-based. All your options and equities in each symbol get linked together. Then the OCC shocks up/down 15% in 5 intervals. The max loss is the margin requirement from the OCC. Your broker can ask for more but not less. One equity position does not offset another but some indexes have offsets. Eg SPX vs SPY.