This OFGEM chart shows the dual-fuel gas and electricity pre-tax domestic supply margins of the six large suppliers in 2016.
It is based on information reported by the large suppliers to the UK energy market regulator in their annual Consolidated Segmental Statements.
Between 2015 and 2016, profits earned by the six large suppliers continued to vary substantially and showed an increase in the average combined gas and electricity pre-tax domestic supply margin from 4.1% to 4.5%.
Close behind second-place is Perth-based utility SSE (shown in pale blue, second top) with a pre-tax profit margin of 6.95%
These are well above the average Big Six profit margin of 4.48% (shown as dotted line, above)
Scottish Power (shown in dark blue, third from top) also generated a healthy pre-tax profit margin of 5.2% despite showing a decreasing trend.
However, EDF (shown in light blue, second from bottom) – the French-owned nuclear-cum-wind power generator made a loss of almost 1% while N.Power lost more than 6% (shown in deep purple, at foot).
1 Sept 2017