The Open FX trades chart visualises the impact of the FX trades on your account, expressed in your baseline currency.
Each coloured bar shows the net amount of your FX trades in a currency within the relevant calendar period. Net amounts resulting in a positive impact on your account point upwards; net amounts resulting in a negative impact point downwards. If you are both buying and selling a currency within the same calendar period, the total buy and sell amounts are shown as grey bars behind the coloured bar.
For details, hover over the chart to see the precise amounts for a given period. The amount in black is the actual traded currency amount. The amount in grey is the same amount expressed in your baseline currency.