Interest rate paid for negative daily excess cash (margin loan)
If the settings also provide a RiskFreeRateSym then MarginIntPct is added to the current daily interest rate as determined by today's value of the risk-free rate series. In this case, MarginIntPct would typically be positive, e.g. 1.5 if your broker charges 1.5% more than the fed funds rate for margin loans.
If RiskFreeRateSym is provided but MarginIntPct is not provided or is 0 then no margin interest is charged. You must specify a non-zero value of MarginIntPct to include margin interest payments in your backtests.
If MarginIntPct is provided when there is no RiskFreeRateSym then MarginIntPct is simply a fixed annual interest rate. In this case the rate should be expressed as a negative number, e.g. -5 to pay margin interest an an annualized rate of 5%.
Daily net interest received or paid is added to combined S.Equity and therefore becomes part of the total return of the backtest.
The stats series S.Interest can be used to graph or reference the cumulative net interest received or paid in the account.
See also CashIntPct which specifies the rate received for positive excess cash.