Under Portfolio Margin, trading accounts are broken into three component groups; Class groups, which are all positions with the same underlying; Product groups, which are closely related classes; and Portfolio groups, which are closely related products. Examples of classes would include IBM, SPX, and OEX. A product example would be a Broad Based Index composed of SPX, OEX, etc. A portfolio could include such products as Broad Based Indices, Growth Indices, Small Cap Indices, and FINRA Indices.
The portfolio margin calculation begins at the lowest level, the class. All positions with the same class are grouped and stressed (underlying price and implied volatility are changed) together with the following parameters:
A standardized stress of the underlying;
■ For stock, equity options, narrow based indices, single stock futures, and mutual funds the stress parameter is plus 15%, minus 15% as well as eight other points in-between.
■ For US market small caps and FINRA market indices the stress parameter is plus 10%, minus 10% as well as eight other points in-between.
■ For Broad Based Indices and Growth indices the stress parameter is plus 6%, minus 8% as well as eight other points in-between.
A market-based stress of the underlying;
■ A five standard deviation historical move is computed for each class. This five standard deviation move is based on 30 days of high, low, open, and close data from Bloomberg excluding holidays and weekends. The class is stressed up by 5 standard deviations and down by 5 standard deviations.
An implied volatility stress for options;
■ Implied volatility for each options class is increased by 15% and decreased by 15%.
In addition to the stress parameters above the following minimums will also be applied:
■ Classes with large single concentrations will have a margin requirement of 30% applied to the concentrated position.
■ A $0.375 multiplied by the index per contract minimum is computed.
■ The same special margin requirements for OTCBB, Pink Sheet, and low cap stocks that apply under Reg T, will still apply under Portfolio Margin.
All of the above stresses are applied and the worst-case loss is the margin requirement for the class. Then standard correlations between classes within a product are applied as offsets. As an example, within the Broad Based Index product 90% offset is allowed between SPX and OEX. Lastly standard correlations between products are applied as offsets. An example would be a 50% offset between Broad Based Indices and Small Cap Indices.
For stocks and Single Stock Futures offsets are only allowed within a class and not between products and portfolios. After all the offsets are taken into account all the worst-case losses are combined and this number is the margin requirement for the account. For a complete list of products and offsets, see the Appendix-Product Groups and Stress Parameters section at the end of this document.
Place Trade’s real-time, intra-day margining system enables us to apply the Day Trading Margin Rules to Portfolio Margin accounts based on real-time equity, so Pattern Day Trading Accounts will always be able to trade based on their full, real-time buying power.
Because of the complexity of Portfolio Margin calculations it would be extremely difficult to calculate margin requirements manually. We encourage those interested in Portfolio Margin to use our TWS Portfolio Margin Demo to understand the impact of Portfolio Margin requirement under different scenarios.
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