Moving averages

A moving average is one of the oldest and most widely used tools in technical analysis. Its job is simple: it smooths out short-term price noise so the underlying direction is easier to see. Many other indicators are built on moving averages, so understanding them well is the foundation for the rest of this section.

SMA versus EMA

A simple moving average (SMA) adds up the closing prices of the last N periods and divides by N. A 20-day SMA is the average of the last 20 closes, and every day carries equal weight.

An exponential moving average (EMA) gives more weight to recent data. As a result it reacts faster when price changes direction, but it also produces more false signals in choppy, directionless markets. The SMA is calmer and slower, yet less easily fooled by brief spikes.

Both are lagging tools: they are calculated from past prices and do not forecast the future. The longer the period, the smoother the line and the greater the lag.

Moving average crossovers

A common approach uses two averages of different lengths, for example 50 and 200 periods. When the shorter average crosses above the longer one, some traders read it as a strengthening uptrend; the opposite cross suggests weakness. These events are popularly called the "golden cross" and the "death cross".

Keep in mind that crossovers usually arrive after a good part of the move has already happened, and in sideways markets they whipsaw back and forth repeatedly. They work better as confirmation that a trend may have changed than as a precise entry point.

Moving averages as dynamic support and resistance

In strong trends, price sometimes pulls back towards a moving average and then resumes in the trend direction. That is why traders call moving averages dynamic support or resistance: unlike horizontal lines, they move along with price. This behaviour is a tendency, not a rule, and different averages may appear relevant in different markets and timeframes. Note also that crypto trades around the clock while forex closes at the weekend, so a "200-day" average covers a different stretch of activity in each market; take this into account when choosing a period.

Key takeaways

• The SMA weights all periods equally and is smoother; the EMA responds faster to new data.
• All moving averages lag and are not forecasting tools.
• Crossovers produce many false signals in ranging markets.
• Moving averages can act as dynamic support and resistance, but not reliably every time.