Money management models are external systems used to calculate position sizing in trading strategies. While there are several standard models provided, users can also create their own custom models (detailed instructions can be found in the relevant chapter). Below are the standard models available:

• FixedContract: This model assumes that the quantity for any trade is constant, regardless of changes in account equity or market conditions.
  
  

• FixedFractional: Defines the trade size (or risk) as a fixed fraction of the account equity. This means the position size adjusts with changes in the equity balance.
  
  

• FixedRatio: This model increases the position size based on the account's profit and loss. As the account balance grows, so does the position size, and vice versa.
  
  

• MeasureFixedFractional: A variant of the Fixed Fractional model, this approach increases the position size after a predefined amount of capital growth, rather than after each trade or a set period.
  
  

• PeriodicalFixedFractional: In this variation of the Fixed Fractional model, the risked percentage is recalculated periodically (e.g., daily, weekly, or monthly) based on changes in account equity, rather than after each trade.
  
  

• ProfitFixedFractional: This model determines the dollar amount risked on a trade as a percentage of the starting account equity plus a percentage of the total closed trade profit.

These models provide flexible options for traders to manage their risk and optimize their position sizing based on different strategies and market conditions.