[spfzero]

As a counter-argument, you usually need to read a lot into the reported numbers, for example read the 10K notes for multiple years in the past. That's the only way to know that the 3B in assets showing up on the balance sheet for "goodwill", to use one easy example, are not really worth 3B. There are many more-nuanced factors that work alike. The reported numbers are what the accountants think might fly under GAAP, and the accountants work for the CEO, who has a say in the accounting "intent".

To test whether markets are perfectly efficient, just look for large movements over time. If a stock goes up 20% in a year, the market might have undervalued it last year, or is overvaluing it this year. It's unlikely the it was correctly valuing it at both times. In the absence of a Covid-19 pandemic, act of god, etc. of course.

You could say that the market just takes "investor sentiment" into account, and is therefore still efficient. But value investing is a strategy that looks for misplaced investor sentiment and exploits it. If that's the way you define an efficient market, than I'd say an efficient market is no obstacle to a value investor.

[vlovich123]

> If a stock goes up 20% in a year, the market might have undervalued it last year, or is overvaluing it this year. It's unlikely the it was correctly valuing it at both times. In the absence of a Covid-19 pandemic, act of god, etc. of course.

Or the company has grown its revenue by 20% in 1 year which isn't necessarily unheard of. Or they significantly beat the expectations of analysts / their own guidance. In all of those cases the stock could have been correctly valued & still experienced growth.

[spfzero]

Sure which is why I said "unlikely", rather than "unheard of".

[nradov]

A 20% rise in a stock doesn't constitute evidence of market inefficiency. In most cases that increase is due to new information becoming available.

If you say that value investing still works then where is the evidence?

[corethree]

>To test whether markets are perfectly efficient, just look for large movements over time. If a stock goes up 20% in a year, the market might have undervalued it last year, or is overvaluing it this year. It's unlikely the it was correctly valuing it at both times. In the absence of a Covid-19 pandemic, act of god, etc. of course.

This is technical analysis not value investing.

[spfzero]

It's not the investment thesis, it's a thought experiment to test market efficiency. It's a test to see whether markets are always efficient, and to me demonstrates that they are not, and that value investing might be an interesting thesis to pursue still.

People have been saying for decades that value investing is not possible since the market is too efficient. My point is that it is not efficient enough to prevent value investing from being a successful strategy.