Reg-T (standard)

• Long stock: 50% initial, 25% maintenance
• Short stock: 150% initial (50% margin + 100% proceeds)
• Long option: 100% of premium
• Short option (naked call): max(20% × stock − OTM, 10% × stock) + premium
• Short put (CSP): strike × 100 (cash secured)
• Vertical spread: max loss × contracts

Portfolio Margin (≥$125k)

• Risk-based: portfolio stress-tested ±15% across products
• Often 1.5–3× more buying power than Reg-T
• Hedged positions get net margin (e.g., long stock + put = stock − put delta)
• Available at most major brokers w/ approval + min equity