Moving averages are probably the most widely used indicator in technical analysis. They appear on nearly every trading chart, they're included in almost every introductory trading course, and they're referenced constantly in market commentary. Precisely because they're so ubiquitous, it's worth stepping back and thinking carefully about what they actually measure, where they genuinely add value, and where they create a false sense of clarity.
What a Moving Average Actually Is
A moving average calculates the average price over a defined number of recent periods and plots that value as a line on the chart. As each new period closes, the oldest period drops out of the calculation and the newest one enters — the window "moves" forward through time, which is where the name comes from.
The most common version is the simple moving average (SMA), which weights each period equally. A 20-period SMA on a daily chart is simply the average closing price of the last 20 trading days. Other variants, like the exponential moving average (EMA), weight recent periods more heavily, making the line more responsive to recent price changes.
The practical effect of any moving average is to smooth out the noise in raw price data. Day-to-day price movements are influenced by temporary factors — short-term order imbalances, reactions to minor news, random fluctuation. By averaging across multiple periods, a moving average filters out much of that noise and reveals the underlying trend more clearly.
Where Moving Averages Add Genuine Value
The most legitimate use of a moving average is trend identification. When the price is consistently above a long-period moving average and the moving average itself is sloping upward, that's a concrete, quantifiable signal that the recent trend has been upward. When the price crosses below and the average flattens or turns down, the trend may be changing. These observations are simple, but they're grounded in actual price data rather than interpretation.
Moving averages also serve a useful role as dynamic reference levels. Unlike a fixed support or resistance line drawn at a specific price, a moving average adjusts continuously as prices move. In a trending market, prices often pull back to a moving average and then resume the trend — not because of any mystical property of the average, but because many participants are watching the same level and placing orders near it.
This self-fulfilling dynamic is real and worth taking seriously. When a large number of traders treat a specific moving average as a support or resistance level, their collective behavior makes it function as one. The 200-day moving average, for example, is watched closely enough by institutional participants that it genuinely influences where buying and selling cluster.
Where Moving Averages Fall Short
Moving averages are lagging indicators. They're calculated from past prices, which means they can only confirm what has already happened — they can't predict what comes next. A moving average crossover signal fires after the price has already moved, which means you're always entering after the initial move rather than at its beginning.
In trending markets, this lag is manageable because the trend persists long enough for the delayed entry to still be profitable. In choppy, directionless markets, the lag becomes a serious problem. The price repeatedly crosses back and forth across the moving average, triggering signals in both directions, most of which quickly reverse. This produces a pattern of frequent small losses that can add up significantly — a phenomenon traders call "getting whipsawed."
No parameter setting eliminates this tradeoff. A shorter moving average period is more responsive but generates more false signals in choppy conditions. A longer period filters out more noise but introduces more lag in trending conditions. The right choice depends on the specific market environment and how the indicator is being used.
How Moving Averages Were Used in This System
In the signal detection system described in this series, a specific moving average — calculated from 144-tick candles rather than daily bars — serves as a secondary signal layer. After a stock has already generated a primary breakout signal, the system tracks whether the price subsequently crosses above this moving average after pulling back below it.
The choice to use a tick-based moving average rather than a time-based one was deliberate. The rest of the system is built on tick data, and maintaining consistency in the underlying candle structure avoids the situation where two indicators are measuring price in fundamentally different ways. A tick-based moving average also updates continuously throughout the trading day rather than resetting at fixed intervals, which keeps it relevant for intraday analysis.
The secondary signal doesn't replace the primary breakout signal — it adds an additional layer of confirmation for stocks that remain in the tracking window after the initial signal. A price recrossing above a meaningful moving average after a pullback is a useful data point about whether momentum is being sustained or fading.
Today's Investing Insight — The Golden Cross and Death Cross
Two of the most widely discussed moving average signals are the golden cross and the death cross. A golden cross occurs when a shorter-period moving average crosses above a longer-period moving average — most commonly when the 50-day crosses above the 200-day. A death cross is the opposite: the shorter average crosses below the longer one. The golden cross is often cited as a bullish signal; the death cross as a bearish one.
In practice, both signals are significantly lagging — by the time the crossover occurs, the underlying trend has typically been in place for weeks or months. Academic research on whether trading these crossovers produces reliable excess returns has produced mixed results at best. Their primary value may be less as actionable signals and more as a clear, widely understood shorthand for describing the broad trend. When commentators say "the index just generated a death cross," they're providing a concise description of where short-term momentum sits relative to longer-term momentum — a useful observation, even if acting on it directly is rarely straightforward.
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This post documents a personal journey of building an algorithmic trading system and is not a recommendation of any specific stock or strategy. Moving averages and other technical indicators do not predict future price movements, and all investment decisions and their outcomes are the sole responsibility of the investor.
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