The max overall simulated drawdown limit for the TopTier Pro Challenge is based on your initial simulated balance and is 10% (8% with the "8% Hybrid Max Loss / Profit Target" add-on) of that value.
For example, if you have an initial sim balance of $100,000.00, your max overall sim drawdown limit would be $10,000.00. Meaning that your sim account's equity would not be allowed to go below $90,000.00.
Another example would be if you had an initial sim balance of $100,000.00 but your current sim balance is $150,000.00, your max overall sim drawdown limit would still be $10,000.00 which is based on your initial sim balance. Meaning that your sim account's equity would not be allowed to go below $90,000.00.
A simple way to calculate the max overall sim drawdown is:
Initial Sim Balance X 0.10 = Drawdown Limit
Initial Sim Balance - (Initial Balance X 0.10) = Drawdown Equity Limit
Note that exceeding the max overall simulated drawdown limit will result in the automatic failure/breach of your account.