What Is the Formula for Calculating Initial Margin under a Standard Portfolio Margining Model?

The standard formula involves calculating the theoretical profit and loss (P&L) of a portfolio across a range of predefined stress scenarios for the underlying asset (e.g. price movements, volatility changes). The initial margin is then set as the largest potential loss (worst-case scenario) identified in these simulations, plus an add-on for liquidity or concentration risk.

This approach is often called the 'SPAN' or 'VaR' method.

How Do Margin Models Account for Concentration Risk during a Stress Period?
Define ‘Variation Margin’ and Its Relationship to ‘Initial Margin’.
How Is the Risk-Based Margin for a Portfolio of Options Calculated?
How Does the SPAN Margin System Facilitate Portfolio Margining?
How Is Value at Risk (VaR) Used in Setting Position Limits?
How Is the Standard Portfolio Analysis of Risk (SPAN) Methodology Used to Calculate Initial Margin?
What Is the Main Objective of the SPAN Margining System?
What Is the Basic Concept behind the SPAN Margining System?

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