12. MOVING AVERAGES

In the realm of technical indicators, moving averages are extremely popular with market technicians and with good reason.Moving averages smooth the price action and make it easier to spot the underlying trends. Precise trend signals can be obtained from the interaction between a price and an average or between two or more averages themselves. Since the moving average is constructed by averaging several days’ closing prices, however, it tends to lag behind the price action.The shorter the average (meaning the fewer days used in its calculation), the more sensitive it is to price changes and the closer it trails the price action. A longer average (with more days included in its calculation) tracks the price action from a greater distance and is less responsive to trend changes. The moving average is easily quantified and lends itself especially well to historical testing.Mainly for those reasons,it is the mainstay of most mechanical trend-following systems.

Popular Moving Averages
In stock market analysis, the most popular moving average lengths are 50 and 200 days. [On weekly charts, those daily values are converted into 10 and 40-week averages.] During an uptrend, prices should stay above the 50-day average. Minor pullbacks often bounce off that average, which acts as a sup-port level.A decisive close beneath the 50-day average is usually one of the first signs that a stock is entering a more severe
correction. In many cases, the breaking of the 50-day average signals a further decline down to the 200-day average. If a market is in a normal bull market correction,it should find new support around its 200-day average. [For short-term trading purposes, traders will employ a 20-day average to spot short-term
trend changes].

Bollinger Bands
These are trading bands plotted two standard deviations above and below a 20-day moving average. When a market touches (or exceeds) one of the trading bands, the market is considered to be over-extended. Prices will often pull back to the moving average line.

Moving Average Convergence Divergence (MACD)
The MACD is a popular trading system. On your computer screen, you’ll see two weighted moving averages (weighted moving averages give greater weight to the more recent price action).Trading signals are given when the two lines cross.