The minimum equity required to open a new margin position. Higher than maintenance margin. For options, initial margin depends on the strategy and whether it's defined or undefined risk.
⚡ KEY TAKEAWAY: Initial margin determines how much you can trade. Defined-risk spreads require only the max loss as margin. Undefined-risk positions (naked puts/calls) require significantly more.
Why It Matters
Initial margin determines your maximum position size. For defined-risk strategies (spreads), it's simply the max loss. For undefined-risk (naked options), it's significantly more — limiting how many contracts you can sell.
How It Works
The minimum equity required to open a new position. Higher than maintenance margin. Reg-T: ~20% of underlying minus OTM amount. Portfolio margin: risk-based (typically 30-50% less). Defined-risk: max loss of the spread.
Example
Opening a 10-lot naked SPY $565 put (SPY at $580). Reg-T initial margin: ~$10,100 per contract = $101,000. The same trade as a $565/$560 put spread: initial margin = $500 per spread × 10 = $5,000. The spread frees up $96,000.
Common Mistakes
Being surprised by margin requirements on naked options. A single naked SPY put can require $10K+ of margin. Always check margin impact before submitting — most brokers show this in the order preview.
The minimum equity required to open a new margin position. Higher than maintenance margin. For options, initial margin depends on the strategy and whether it's defined or undefined risk.
Why does Initial Margin matter for premium sellers?
Initial margin determines how much you can trade. Defined-risk spreads require only the max loss as margin. Undefined-risk positions (naked puts/calls) require significantly more.
How does Initial Margin work?
The minimum equity required to open a new position. Higher than maintenance margin. Reg-T: ~20% of underlying minus OTM amount. Portfolio margin: risk-based (typically 30-50% less). Defined-risk: max loss of the spread.
What are common mistakes with Initial Margin?
Being surprised by margin requirements on naked options. A single naked SPY put can require $10K+ of margin. Always check margin impact before submitting — most brokers show this in the order preview.
