History seems to be repeating itself and in relatively short order. The recent rally has driven a sharp rise in the market capitalisation of companies trading at enterprise value (EV) to sales ratios above 10 or 20 times – i.e., stocks where the market is willing to pay extraordinarily high prices relative to the companies' revenue. Today, over 20% of weight in the MSCI World has an EV/sales ratio greater than 10! That's back in dotcom bubble territory.