Warren Buffett has published his latest annual letter for investors in Berkshire Hathaway (see http://berkshirehathaway.com/letters/2018ltr.pdf). These letters are always worth reading for their insight into how a successful stock market investor thinks. I’ll pick out a few highlights: Berkshire’s per share book value only rose by 0.4% in 2018 but he assigns that to the need to write down $20.6 billion on his investment holdings in unlisted companies due to new GAAP accounting rules using “mark-to-market” principles. He is not happy about ...