We often hear market commentators croaking about the number of stocks going up vs. those going down. There is even an advance/decline line filed under technical “analysis.” However, have a look at the statistical distribution of stocks going up in any given month and see for yourself if it makes any sense paying attention to it:
It is, at best, a historical artifact… something that is nice to lookup when someone says that they had a great/crappy month. When a lot of stocks have gone up, it presents a target rich environment for long-only traders. So a random selection of stocks would out-perform the index in that scenario. But good luck using it for market timing.
Code and chart are on github.