> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Additional Initial Margin

This document provides a walkthrough of the additional margin implementation in Atoti ISDA-SIMM.

The total SIMM formula per para 6 of the SIMM Version 2.2 $SIMM = SIMM_{RatesFX} + SIMM_{Credit} + SIMM_{Equity} + SIMM_{Commodity}$ can be extended to include regulatory-specific or netting set-specific factors, which will increase the IM amount.

## Additional Margin formula

The additional margin is calculated as follows:

$Additional IM = AddOnFixed + AddOnNotional + AddOnSIMM$

where:

* $AddOnFixed = Param_AddOnFixedAmount$
* $AddOnNotional = \sum_{p \in products} Param\ AddOnNotionalFactor_p \cdot Notional_p$
* $AddOnSIMM = \sum_{pc \in product\ classes} Param\ ProductClassMultiplier_pc \cdot SIMM_{pc}$

## Additional Margin Parameters

A set of the Additional Margin parameters consists of:

* Param\_AddOnFixedAmount (default 0)
* Param\_AddOnNotionalFactor (default 0)
* ProductClassMultiplier\_pc (default 1)

To allow for regulatory-specific and netting set-specific parameters, and to minimize the maintenance effort, the following waterfall logic is implemented:

* case 1. Only Regulator is specified (Post or Collect) - apply to all SIMM for that regulator in any of the agreements.
* case 2. Only Netting Set is specified - override parameters for that netting set, ignore the regulator.
* case 3. Netting Set and Regulator is specified - override parameters only for the netting set and the regulator.