Whether a tiny start-up, a giant conglomerate or an investor whose interests straddle tech and breakfast, the same killer question eventually arrives: should a company that manufactures a famously fabulous toaster also have a crack at building mobile phones?

Versions of this conundrum are staples of business school lectures. Tiffany & Co did well adding jewellery to its original line-up of stationery; Berkshire Hathaway looked smart bolstering textiles with insurance. We revere these stories when they work, and dismiss them as reckless when they fail.

Financial Times