Margin

Margin in the builder

The builder’s Margin column is the most that row can lose by its front expiration: dollars, “Unlimited” when the loss has no limit, or $0 when the structure cannot lose. It uses the same exact or in-range rule as Max L. PnL% is PnL as a percent of this Margin.

Note

Margin here is a structural worst case from the legs, not the margin your broker holds or requires. For IB’s own figure after an order, see “Excess after” in Lots and limit price.

Plan margin

Gear menu → Settings → Trading → Plan margin (Max, Current, Original, default Max) sets what a plan’s “% of margin” target or stop measures:

• Max: the most risk the trade has carried at any point. If any step is unlimited or unknown, the margin is unknown.
• Current: the trade’s risk now.
• Original: the risk right after the entry fill.

Only “% of margin” follows the setting. “% of max loss” and the trade flags stay on the current risk. For plans, a position across expirations reads the front expiration with later long legs at intrinsic value, so a calendar risks its debit; a later short leg leaves both bounds unknown. A stop set as a percent of margin therefore moves with this setting. See Plans and alerts.

If a plan reads “% of margin · not on this trade”, see % of margin · not on this trade. If the builder’s Margin differs from IB’s, see The builder Margin differs from my IB margin.