This is a few weeks old but nonetheless, very interesting (and important) article from Aswath Damodaran on what really is not valuation but your investment process. Below is an excerpt.

If you believe that the stock market is in a bubble, you have lots of company. You have long-time market watchers, the New York Times and even a Nobel Prize winner in your camp. But what exactly is a bubble? How can you tell if you are in one?  And if you do believe you are in a bubble, what is your best course of action? Not only are these questions difficult to answer, but the answers can vary across markets, investors and time.

The Bubble Machine

Every market has a bubble machine, though it is less active in some periods than others, and that machine creates an ecosystem of metrics and experts, as well as warnings about bubbles about to burst, corrections to come and actions to take to protect yourself against the consequences. 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.

  1. 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). They remind me of this character from Winnie the Pooh and their theme seems to be that stocks are always over valued.
  2. Knee Jerk Bubblers go into hibernation in bear markets but become active as stocks start to rise and become increasingly agitated, the more they go up. They are the Bobblehead dolls of the bubble universe, convinced that if stocks have gone up a lot or for a long period, they are poised for a correction.
  3. Armchair Psychiatrist Bubblers use subtle or not-so-subtle psychological clues from their surroundings to make judgments about bubbles forming and bursting. 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.
  4. Conspiratorial Bubblers believe that bubbles are created by small group of evil people who plan to profit from them, with the Illuminati, hedge funds, Goldman Sachs and the Federal Reserve as prime suspects. Paranoid and ever-watchful, they are convinced that stocks are manipulated by larger and more powerful forces and that we are all helpless in the face of this darkness.
  5. Righteous Bubblers draw on a puritanical streak to argue that if investors are having too much fun (because stocks are going up), they have to be punished with a market crash. As the Flagellants in the bubble world, they whip themselves into a frenzy, especially during market booms.
  6. 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. Viewing themselves as smarter than the rest of us and also as the voices of reason, they view their metrics as infallible and mean reversion in markets as immutable.

There are three things to keep in mind about bubblers. The first is that bubblers will receive disproportionate attention in the media, for the same reasons that a reality show about a dysfunctional family will have higher ratings than one about a more normal family. The second is that even the most misguided bubblers will be right at some point in time, just as a broken clock is right twice every day. The third is that being right is often the worst thing that can happen to bubblers, because it seems to feed into the conviction that they are always right and leads to increasingly bizarre predictions. 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.

Defining a Bubble

What is a bubble? The lazy definition is that any time you see a large market correction, it is the result of a bubble bursting, but that is neither a useful definition, nor is it true. To me, a bubble reflects a market disconnect from fundamentals, where prices go up steeply, with no help from the fundamentals. The best way of illustrating this is to go back to an intrinsic value model, where the value of stocks can be written as a function of three fundamentals: the base year cash flows that investors are receiving, the expected growth in these cash flows and the risk in the cash flows:

Bubble

 

 

See full article on Bubble, Bubble, Toil and Trouble: The Costs and Benefits of Market Timing by Aswath Damodaran