Not sure if this economist article is behind paywall or not. It pierced a hole into the WB myth:
The industrial arm’s operating performance is bog standard and, once you include the goodwill, its ROE is a weak 6%, down from 9% in 2007 before Berkshire shifted course (these sums exclude the amortisation of intangible assets, which is in accordance with how Mr Buffett assesses profits).
The industrial businesses’ lacklustre record mean they account for about 60% of Berkshire’s sunk capital but have generated only about half of its look through profits, and 40% of its growth in book value over the past five years. For the five big industrial companies where figures are consistently available, total profits have risen by 4% a year since 2012, which is no better than a basket of similar peers. Profits at BNSF, for example, have risen only just above inflation and in line with other railways.