Open trade with no commission

[Pierre Cilliers 0]

Hi all.

Just a real quick one.

I have set my broker commission as follows (for example) - aim was to have a fixed commission for each trade:

cerebro.broker.setcommission(commission=0.015, leverage=100, commtype=bt.CommInfoBase.COMM_FIXED)

I successfully open a buy_bracket order as follows:

self.buy_bracket(tradeid = 1,
            exectype = bt.Order.Market,
            price = action_info['price'],
            size = 0.01, 
            limitprice = action_info['take_profit'],
            stopprice = action_info['stop_loss'])

This order will obviously be immediately filled at Market price as I have selected bt.Order.Market and the broker commission will be assigned to it.

My question relates to modifying an existing order. As Backtrader does not have that built-in yet, I close my existing order and open a new one with the modified stoploss and/or takeprofit.

My logic goes something like this for a trade with tradeid = 1:

self.close(tradeid = 1, size = 0.01)
self.buy_bracket(tradeid = 1,
            exectype = bt.Order.Market,
            price = action_info['price'],
            size = 0.01, 
            limitprice = action_info['new_take_profit'],
            stopprice = action_info['new_stop_loss'])

I therefore will be charged with another commission when this trade is modified. Is there a way to open a buy_bracket order with commission = 0 even though I have set it in setcommission?

I was thinking of doing the followingf, but it doesn't work:

self.close(tradeid = 1, size = 0.01)
self.buy_bracket(tradeid = 1,
            exectype = bt.Order.Market,
            price = action_info['price'],
            size = 0.01, 
            limitprice = action_info['new_take_profit'],
            stopprice = action_info['new_stop_loss'],
            commission = 0.0)

Thanks for your time. Hope this is clear enough.

Tagging @backtrader @EMR as they pretty active and helpful

[Pierre Cilliers 0]

and @run-out Many thanks guys

[Pierre Cilliers 0]

Hi all.

Managed to get this right by redefining the broker commission each time I want to modify my order (meaning I want to close and reopen an order with different parameters with zero commission).

The procedure I followed was to refine the setcommission as follows:

self.broker.setcommission(commission=0, leverage=self.leverage, commtype=bt.CommInfoBase.COMM_FIXED)
self.close(tradeid = 1, size = 0.01)
self.buy_bracket(tradeid = 1,
            exectype = bt.Order.Market,
            price = action_info['price'],
            size = 0.01, 
            limitprice = action_info['new_take_profit'],
            stopprice = action_info['new_stop_loss'],
            commission = 0.0)

NB! Just remember to reset your commission scheme before opening real market orders again.

Additional checks:

• The way I checked whether this works is by outputting the comminfo after setting the commission to my desired value.
• this can be done as follows (in python):

self.broker.setcommission(commission=self.commission, leverage=self.leverage, commtype=bt.CommInfoBase.COMM_FIXED)
print(self.broker.comminfo[None].params.__dict__) # should print your broker's commission fee
self.broker.setcommission(commission=0, leverage=self.leverage, commtype=bt.CommInfoBase.COMM_FIXED)
print(self.broker.comminfo[None].params.__dict__) # should print zero commission fee

Hope this helps. Just tag me if you have any further questions or alternative tips