In periods like the current one, when the bubble machine is in over drive and you are confronted by "bubblers" with varying credibilities, motives and methods, you may find it useful to first categorize them into the following groups. And one does not know how big this latest investment bubble will go until it bursts but you can expect them to continue for a few years yet, as the struggles in China intensify, Europe breaks up over Brexit, Japan starts to look like a giant helicopter, the rest of Asia struggles along and the rest of this world in Australia and New Zealand move along at a modest pace. They are the Bobblehead dolls of the bubble universe, convinced that if s have gone up a lot or for a long period, they are poised for a correction. It is no coincidence that every market correction in history has created its gurus (who called that correction right) and those gurus have almost always found a way to discredit themselves ahead of the next one. Rational Bubblers uses market metrics that are both intuitive and widely used, note their divergence from historical norms and argue for a correction back to the average.
As the Flagellants in the bubble world, they whip themselves into a frenzy, especially during market booms. Freudian in their thinking, they are convinced that any mention of stocks by shoeshine boys, cab drivers or mothers-in-law is a sure sign of a bubble. There are three things to keep in mind about bubblers. If cash flows increase, growth rates surge, risk free rates drop or macroeconomic risk subsides, stocks should go up, and sometimes steeply, and there is no bubble. Doomsday Bubblers have been warning us that the stock market is in a bubble for as long as you have known them, and either want you to keep your entire portfolio in cash or in gold (or bitcoins). To me, a bubble reflects a market disconnect from fundamentals, where prices go up steeply, with no help from the fundamentals. At the other extreme, if stock prices go up as cash flows decrease, growth rates become more negative and risk free rates and equity risk increase, you have a bubble. Moreover, at 15 times earnings, a more appropriate valuation for a company with such earnings power, MRNA stock will be worth much more.