Expected earnings vs actual earnings

The stock market moves on expectations, not on its actual performance. If the market expects Firm A to grow its earnings by 20% for the next 5 years, the stock will rally 100% in the next 5 weeks. It does not matter if Firm A can actually grow its earnings 100% after 5 years. Similarly, if the street expects Firm B to miss its forecast, Firm B's stock will not wait for the announcement and then plunge. It will plunge today.

For the lack of a better way to describe this market phenomenon, I used earnings, but it can apply to everything, from favourable regulation changes to M&A rumours. The stock moves on what the collective thinking of all the investors point towards to and not the actual scenario that will eventually play out. If one can understand this, it is easy to see that this phenomenon has two impact:

1) The market may be wrong, but since the actual scenario does not happen immediately, at the meantime, the market is right. Hence the saying "the market is always right".

2) The market may be right, but it will almost always overreact (e.g. factoring 5 yrs of earnings in 5 weeks) and the scenario is played out in a shorter time frame than expected.

In the long run, the market moves towards the actual scenario and the market corrects its past mistakes. Hence value investing, by trying to estimate the intrinsic value of the company, stands the test of time and the idiosyncracies of the market.