The Moving Average: A Complete Guide for Stock Investors

The moving average is one of the key tools in technical analysis, highly valued by investors in financial markets. This indicator helps to smooth out price fluctuations, clearly identify underlying trends, and improve investment decisions. In this comprehensive guide, we will explain in depth how moving averages work, their practical utility in the stock market, illustrate with a real example from the British market, and detail how to benefit from strategies related to this indicator. You will also discover pitfalls to avoid, practical cases with figures, and advanced tips for effectively integrating the moving average into your analysis.

What is a Moving Average?

The moving average, or MA in English, is a statistical calculation that follows the average evolution of a stock price over a given period. Its main purpose is to reduce the variability of short-term prices, often caused by random or emotional factors, to highlight the general trend. It is called "moving" because at each new data point (usually each trading session), the average is recalculated over the considered period by excluding the oldest data and including the newest.

Definition and Calculation

To calculate a simple 20-day moving average, you add up the closing prices of the last 20 days and then divide by 20. When a new trading day is added, the oldest price is removed from the calculation, and the price of the new day is included. This process produces a smoother curve than the raw price chart, allowing the underlying trend of the stock to be isolated.

Suppose we are evaluating the stock MONY Group PLC (MONY.L) on the London Stock Exchange. If we take a 50-day moving average, it is the arithmetic mean of the last 50 closing prices in pence sterling (GBX). For example, at the end of August 2025, the average price closed around 200 GBX. This means that the 50-day moving average would be near this level if no major changes had occurred.

The Different Types of Moving Averages

  • Simple Moving Average (SMA): Arithmetic mean, the most commonly used due to its ease of calculation and effectiveness over the long term.
  • Exponential Moving Average (EMA): Gives more weight to recent prices, making it more sensitive to rapid changes in trend. It is preferred by reactive investors, especially for short-term trading and volatile markets.
  • Weighted Moving Average (WMA): Assigns a variable weight to each price, generally favoring recent prices, but according to a linear rather than exponential weighting.

The choice of moving average type depends on the investment horizon and the desired level of responsiveness. The SMA remains the reference for long-term trend analysis, while the EMA appeals to traders seeking faster signals.

Why Use the Moving Average in the Stock Market?

The moving average offers several advantages to investors and traders:

  • Clear visual analysis of market trends by filtering out short-term "noise".
  • Generation of precise buy and sell signals through crossover or breakout rules of moving averages.
  • Identification of potential support and psychological resistance zones.
  • Flexibility to all time horizons and assets: stocks, indices, currencies, commodities, cryptocurrencies.
  • Ease of integration into automated strategies or disciplined investment plans.

Moving Average and Trend Detection

One of the major uses is to identify the predominant direction of the market:

  • Bullish trend: The price evolves above its 50 or 200-day moving average.
  • Bearish trend: The price evolves below its moving average over the same period.

Let's again consider the concrete case of MONY Group PLC, a British internet equipment manufacturer, which has a market capitalization of £1 billion on November 11, 2025, and whose stock price fluctuates between 174 pence and 218.6 pence this year. If the closing price consistently exceeds the 50-day moving average, which stands at 200 pence, the trend is considered bullish. Conversely, falling below this level reinforces the signal of a possible correction or a return to a bearish trend.

Crossing Moving Averages Analysis

The crossing of moving averages is a powerful mechanism for generating signals:

  • Bullish crossover (Golden Cross): When the shorter moving average (e.g., 50 days) crosses above the longer one (e.g., 200 days). This indicates the start of a significant upward movement.
  • Bearish crossover (Death Cross): When the shorter moving average crosses below the longer one. This is often seen as a warning of an extended bearish trend.

These signals are followed by most traders because they accompany significant capital flows, making post-crossover movements more meaningful. However, they require sufficient volume and a non-excessive volatility context.

Moving Average as Support and Resistance Level

Investors also scrutinize the moving average as a psychological barrier:

  • Support: When a stock rebounds upwards after touching its moving average (example: a test on the 200-day during a bearish retracement).
  • Resistance: When a price hesitates to break above the moving average.

These levels are used to place stop-loss or take-profit orders, thereby limiting risk or securing profits.

Case Study: Practical Application on MONY Group PLC

To illustrate the practical use of moving averages, let's take the example of a London-listed company: MONY Group PLC (MONY.L).

Financial Data and Context

  • Market Capitalization in November 2025: £1.06 billion (approximately €1.22 billion according to the exchange rate at the time).
  • Current Price: ranging from 198 GBX early March 2025, 214 GBX early June, 197.10 GBX in September, averaging around 200 GBX over the summer period.
  • Annual Variation: the price varies between 174 GBX and 218.6 GBX throughout 2025, reflecting moderate but significant volatility for the sector.
  • PER (Price/Earnings Ratio) 2025: 12.2x
  • Estimated PER 2026: 11.2x

Imagine you are studying the trend on MONY using a 50-day simple moving average. In August 2025, the average price is around 200 GBX. If the stock price crosses the 50-day moving average, it may signal a reversal or acceleration of the trend. It is crucial to analyze such signals by considering the broader market context and the annual range of prices.

Importance of Choosing the Period for the Moving Average

The period chosen for the moving average impacts its ability to detect relevant signals:

  • A short-term moving average (10 or 20 days) identifies quick reversals but produces more false signals in less volatile markets.
  • An intermediate moving average (50 days) is ideal for tracking trends over several weeks/months and is widely used for "swing trading."
  • A long-term moving average (200 days) filters out short-term noise to capture only the major market cycles, suitable for long-term investors.

In our example, using the 50-day SMA offers a good balance between responsiveness and filtering out noise for a stock like MONY, which exhibits limited monthly variations.

Investment Strategies Based on Moving Averages

Investors use various strategies based on moving averages to optimize their entry and exit points:

1. Classic Rule: Follow the Trend

The most common rule involves buying when the price moves above the selected moving average (for example, the 50-day SMA), and selling when it falls below. This method forms the basis of "trend following" and has shown historical robustness across many financial markets, although it can generate some false signals during flat or non-directional markets.

2. Exploit Crossovers

A variant involves observing two moving averages of different periods (e.g., 20 days and 50 days, or 50 days and 200 days). A buy signal is triggered when the shorter average crosses below the longer one (golden cross), and a sell signal occurs in the opposite case (death cross). This strategy generates fewer false signals and better responds to changes in market cycles.

3. Use Dynamic Moving Average as Stop-Loss

Some investors place their stop-loss order just below the long-term moving average (e.g., the 200-day SMA) to protect a gain in case of a reversal, while allowing the position to breathe so as not to be prematurely exited. This allows for maximizing returns on established trends.

4. Filter by Volatility and Return

One of the frequent limitations of the moving average approach is ignoring volatility: very calm or overly unstable markets can distort the relevance of signals. It may then be useful to couple the moving average with a volatility indicator (such as ATR or standard deviation) or analyze the annualized return to filter truly relevant buy/sell zones. In 2025, MONY Group PLC shows moderate volatility oscillating mainly between 174 GBX and 218.6 GBX over the year, which makes the moving average particularly readable.

5. Backtesting and Historical Performance Comparison

Before integrating a moving average strategy into your investment plan, it is strongly recommended to conduct a backtest on the historical data of the stock. Past performance is of course indicative but not guaranteed, but it allows you to verify the statistical robustness of your rules (buys/sells according to crossover, optimal period, etc.). For MONY Group PLC, which showed a dividend yield of 6.7% in 2025 and relatively stable prices, the trend-following strategy using a 50-day moving average would have limited premature exits during minor corrective movements while participating in the bulk of the rise.

Limits and Pitfalls of Moving Average in Technical Analysis

Despite its popularity, the moving average is not without flaws:

  • Natural lag: the moving average, by construction, reacts with inertia to sudden reversals. A signal may appear late relative to the start of a movement.
  • Fake signals in flat markets: during consolidation phases, crossovers are frequent but rarely followed by marked trends, generating losses if orders are multiplied.
  • Arbitrary choice of periods: the selection of 20, 50, or 200 days is often empirical and must be adapted to each asset as well as the ambient volatility.
  • Independence from volume: the moving average does not take into account the trading volume, yet this factor is decisive for validating the amplitude of a movement.

To avoid these pitfalls, it is recommended to:

  • Combine the moving average with other indicators (MACD, RSI, volume, Bollinger Bands, etc.).
  • Vary the time horizons studied (short, medium, and long term).
  • Always work systematically with a broad history to define the optimal period and level of efficiency of the indicator.
  • Always contextualize the moving average signal within the context of the stock (return, volatility, news, valuation level).

Practical Example of an Automated Strategy Using Moving Average

It is possible to automate your investment strategy around the moving average using technical analysis tools offered by most brokers and online trading platforms. Here is a simple example of code to execute orders on the crossover of SMA 20 and SMA 50 days:

If SMA_20 > SMA_50 then Buy (or maintain a buy position)
otherwise if SMA_20 < SMA_50 then Sell (or exit the position)

This kind of automation avoids emotional biases, imposes strict discipline, and facilitates the management of a multi-asset portfolio.

Frequently Asked Questions about Moving Averages

Which assets do moving averages work best for?

Moving averages can be used on all financial markets: stocks, indices, commodities, currencies, cryptocurrencies. They are particularly reliable on liquid and less manipulated markets where trends are broad enough to avoid false signals.

What period of moving average should I choose?

The answer depends on your time horizon:

  • Short term: SMA or EMA 9/10/20 days.
  • Medium term: 50 days.
  • Long term: 100 or 200 days.

To follow major stock trends, the 200-day SMA remains the reference.

Do moving averages guarantee beating the market?

No, no indicator guarantees superior performance over the market. The moving average helps to avoid periods of strong decline but can generate losses during sideways markets. Adding complementary filters and testing on historical data is essential to improve the potential of the strategy.

Conclusion: Maximizing the Use of Moving Averages

The moving average remains an indispensable tool of technical analysis. It is easy to understand, applicable to all markets and time horizons, it structures trend analysis and entry/exit signals. For investors, its true strength lies in its ability to discipline decision-making, offering a clear reference point in often erratic markets. Its effectiveness, however, depends on the judicious choice of the calculation period, the context of the analyzed security (volatility, yield, news), and especially on its coherent integration into a global strategy, always weighted and diversified. Don't hesitate to test multiple moving averages on your favorite values, cross the signals with other indicators, and adapt your rules according to the investment horizon you aim for.

With a structured approach, the moving average represents a major asset for the success of your long-term equity investments.