Clarification about number of trades and available liquidity

[sotos82]

Hello,
I am new to Backtesting.py and I have the following question:

Within my strategy class I use the following to place an order based on some condition.
self.buy(sl = stopLoss, tp = takeProfit, size= .99999)

Before the run I also set:

bt = backtesting.Backtest(df_Test, MyStrategy, trade_on_close = True, exclusive_orders = False, cash = initialCash)

Here is part of the trading plot

Can someone explain to me why Backtesting starts another trade (see arrow) before the active trade becomes inactive since there is not enough available liquidity because size= .99999 (So if I understand the whole initial capital is committed to the previous trade)??

thanks

[iimka]

You can add condition in front of the self.buy:

for example, from:

if (1 == 1):
    self.buy()

to:

if (1 == 1 and 
not self.position.is_long):
    self.buy()

[sotos82]

Hello, thank you for your answer. I understand about conditions.

My question however was why it initiates another trade if the whole capital is committed to the 1st trade (size = 0.9999) still active and there is no money left.

[iimka]

Maybe your initial cash is too large.

After you buy 99.999% your cash in stocks, your remaining 0.001% cash may still be able to buy a small amount of stock. You can take a look at the Profit/Loss graph to see how much size you bought in the second action.

You can delete the code 'size= .99999' or add the 'not self.position.is_long' to avoid the problem.

[rvk80]

May be your present position is generating some profit which is used for taking the trade. As per documentation If size is a value between 0 and 1, it is interpreted as a fraction of current available liquidity (cash plus [Position.pl] minus used margin).