The $260 million-plus of costs involved with AGL Energy’s proposed demerger may not be offset by savings that would result from the restructuring, say UBS energy analysts. The finding lends weight to criticism being voiced by tech billionaire Mike Cannon-Brookes.

The analysis by UBS analysts Tom Allen and Joseph Wong also cast doubt on whether the split of the giant electricity supplier into coal power-focused Accel and retailer AGL Australia will really result in a “re-rating” of the retailer among financiers, reducing its cost of capital.