1. Core Philosophical Difference: Strategy-Based vs. Risk-Based
The fundamental distinction between Reg T and Portfolio Margin lies in how margin requirements are calculated:
Reg T (Strategy-Based)
Applies fixed percentage formulas to individual positions or predefined multi-leg spreads regardless of how well hedges offset underlying portfolio risk.
Portfolio Margin (Risk-Based)
Evaluates the entire portfolio as a single integrated system, measuring actual maximum potential loss across 10 theoretical market price and volatility shocks.
2. Comprehensive Comparison Matrix
| Feature | Reg T Margin | Portfolio Margin |
|---|---|---|
| Regulatory Authority | Federal Reserve (12 CFR Part 220) | FINRA Rule 4210 / SEC / OCC |
| Initial Margin Requirement | 50% of Stock Purchase Value | 15% to 20% (Based on TIMS Loss) |
| Maximum Equity Leverage | 2:1 Overnight / 4:1 Day Trading | 6.67:1 (up to 10:1 for index products) |
| Minimum Account Equity | $2,000 | $100,000 to $125,000 |
| Option Hedges Recognition | Limited predefined spreads | Full non-linear delta/gamma netting |
3. How the OCC TIMS Model Calculates Margin Requirements
The OCC's Theoretical Intermarket Margin System (TIMS) recalculates the net value of your portfolio across 10 discrete market valuation nodes:
- 1. -12% Underlier Move (Max Downward Shock)
- 2. -9.6% Underlier Move
- 3. -7.2% Underlier Move
- 4. -4.8% Underlier Move
- 5. -2.4% Underlier Move
- 6. Unchanged (Current Market Price)
- 7. +2.4% Underlier Move
- 8. +4.8% Underlier Move
- 9. +7.2% Underlier Move
- 10. +12% Underlier Move (Max Upward Shock)
The largest projected loss across all 10 nodes becomes the precise dollar margin requirement for that asset class.
4. Frequently Asked Questions (FAQ)
Yes, provided you maintain at least $100,000 to $125,000 in account equity, pass a broker options risk assessment, and secure Level 4/5 options trading privileges.
Portfolio Margin permits higher leverage, which can amplify losses rapidly on unhedged positions. However, for properly hedged portfolios, Portfolio Margin provides superior risk accuracy and capital efficiency.