The daily simulated drawdown limit for the TopTier Challenge is based on the day's starting virtual balance and is 5% of the value at 5PM EST.
For example, if you have a virtual balance and equity of $100,000.00 at 5PM EST, your daily sim drawdown limit would be $5,000.00. Meaning that your account's sim equity would not be allowed to go below $95,000.00.
Another example would be if you had a sim balance of $150,000.00 at 5PM EST but your equity was $175,000.00, your daily sim drawdown limit would be $7,500.00 which is based on your sim balance at 5PM EST. Meaning that your account's sim equity would not be allowed to go below $142,500.00.
A simple way to calculate the daily sim drawdown is:
Starting Day's Balance X 0.05 = Drawdown Limit
Starting Day's Balance - (Starting Day's Balance X 0.05) = Drawdown Equity Limit
Note that exceeding the daily sim drawdown limit will result in the automatic failure/breach of your account.