The real answer is because a lot of charting software packages the past few decades have set it as a default.
But you also hear guys like Paul Tudor Jones talk about how below a 200 day moving average, you get out. In other words, bad things happen below the 200 day.
For me, I have reasons for doing everything. And while I understand that there are more like 252 trading days in a year, not 200, I still believe that if a stock is below its 200 day simple moving average, it's probably not in an uptrend.
This is specifically for my personal definition of an intermediate-term timeframe. I like to look out weeks and months, not years, and certainly not hours or days.
200 days is a good number for me. And while it's not perfect (hint: nothing is) looking at the percentage of stocks above their 200 day has historically given us some great washout signals.
If there is one intermarket relationship that every stock market investor should be following, it's got to be the Discretionary vs Staples ratio.
Consumer Discretionary stocks represent those areas where "Consumers" spend their "Discretionary" income. These include Autos, Retailers and Homebuilders, among other things.
Consumer Staples are the stuff consumers are going to buy and use regardless of how bad the economy might get. These are things like Laundry Detergent, Toothpaste, Beer, Chips and Soda.
When Discretionary stocks are outperforming Staples, that historically happens when stocks in general are doing well and the S&P500 is moving towards the upper right of the chart.
When stocks in general are under pressure, Staples tend to outperform, holding up better than most other stocks, especially Consumer Discretionaries.
It's probably the most important correlation for US Stock Market investors to be aware of.
When the worst stocks on the planet can't go down any more, that's usually good information.
We saw a lot of Small-cap Growth, Arkk Funds, Biotech, Chinese Internet and many of those other "Growthy" areas bottom out this Spring, and some of the last ones in June.
At the Mega-cap level, nothing caused more shareholder wealth destruction than Facebook, down 60% from its highs less than a year ago.
The chart below is the one I'm watching the closest.
You guys have been hearing me pound the table about the US Dollar and what a hard time stocks and crypto will (continue to) have in a stronger Dollar environment.
So here you have it. This is the Emerging Markets ETF $CEW back to the same level where it bottomed out the only 2 other times it was ever down here:
If you've been following along over the years, you've heard me mention plenty of times that breadth thrusts tend to cluster together early on in market uptrends.
Well, a funny thing happened yesterday - we had our first 9-to-1 up volume day on the NYSE since May.
To quote Willie, "Stringing 2 of these together without an intervening 9-to-1 down day would be a very positive development".