Indicators

Moving Average: What It Is and How to Use It in Trading

Astron Team · 09/24/2026 · 6 min read

Few indicators are as widely used and as poorly understood as the moving average. Present on practically every charting platform, it helps smooth out the price's erratic behavior, making it easier to see a trend's overall direction. But using the moving average without understanding its limitations can lead to late decisions, precisely because of the indicator's own nature.

This article explains what a moving average is, the main types used by traders, and how to interpret it without falling into the most common traps.

What a moving average is

The moving average is the calculation of an asset's average price over a defined number of periods, updated as each new period passes. For example, a 20-day moving average shows, every day, the average of the closing prices over the last 20 days, dropping the oldest day as a new one is included.

As a result, the moving average line moves more smoothly than the price itself, filtering out some short-term noise and making it easier to see the predominant trend over a given period.

Simple moving average and exponential moving average

Simple moving average (SMA)

Calculates the plain arithmetic average of the prices for the chosen period, giving equal weight to each day within the considered window. It's the easiest type to understand and calculate by hand.

Exponential moving average (EMA)

Gives more weight to more recent prices, making the line react faster to changes in the price's direction, compared to the simple average. This has advantages (faster signals) and disadvantages (more sensitivity to short-term moves that may not represent a real trend change).

How to interpret the moving average in practice

When the price is consistently above the moving average, that's usually interpreted as an uptrend signal; when below, as a downtrend signal. Another common reading is the crossover between two different-period averages: when a shorter average crosses above a longer one, many traders interpret that as a signal of a possible start of a rally, and the reverse crossover as a signal of a possible start of a decline.

A simplified numerical example: for a stock with closing prices of R$ 48, R$ 49, R$ 51, R$ 50, and R$ 52 over the last five days, the 5-day simple moving average would be (48+49+51+50+52) ÷ 5 = 250 ÷ 5 = R$ 50. If the current price is R$ 52, above this average, that's read by many traders as a sign of short-term relative strength.

• The simple moving average gives equal weight to all prices in the period.
• The exponential moving average reacts faster to recent changes.
• An average crossover is used as a signal of a possible trend change.
• Moving averages are lagging indicators, not anticipatory ones.

The main limitation: the indicator's lag

Since the moving average is calculated based on past prices, it always reacts after the move has already started, never before. That means, in markets with no clear trend, oscillating back and forth, the moving average can generate several false crossover signals, each arriving too late to capture the full move.

Combining with other indicators

Because of this natural lag, many traders combine the moving average with other indicators, like the RSI or volume, instead of using it in isolation. The idea is to use the average to confirm the overall direction and another indicator to try to fine-tune the entry timing within that direction.

How to use the moving average in a balanced way

Choose the average's period according to your trade's horizon: shorter periods for short-term trades, longer ones for a broader trend view. Avoid basing an entry decision solely on an average crossover, without considering the market's overall context, and remember that, being a lagging indicator, the moving average works better confirming an already ongoing move than anticipating reversals.

Test different average periods on historical data of the asset you usually trade before adopting a fixed value, since the period that works best for a high-volatility stock may not be the same one best suited for a more stable currency pair. No moving average setting eliminates the risk of false signals, and the indicator should be treated as part of a broader analysis, not as an isolated decision rule.