Technical analysis

MACD

MACD is a price-based momentum indicator that compares two exponential moving averages and uses a signal line to show changes in the strength and direction of a trend.

What it means

Moving Average Convergence Divergence, or MACD, tracks the gap between a faster and a slower exponential moving average (EMA) of a stock’s price. As that gap changes, MACD can help describe price momentum. It does not measure the cost of executing a trade or predict the next price.

A standard MACD display has three parts: the MACD line, a signal line that smooths it, and a histogram showing the distance between those lines. Values are in price units, such as US$ per share, rather than percentages. A MACD of +US$2 therefore has a different relative size for a US$20 stock than for a US$200 stock.

How it is calculated

The common settings use 12, 26 and 9 trading-day periods for a daily chart:

  • EMA_t(N) = α × P_t + (1 − α) × EMA_(t−1)(N); α = 2 / (N + 1)
  • MACD_t = EMA_t(12) − EMA_t(26)
  • Signal_t = EMA_t(MACD, 9)
  • Histogram_t = MACD_t − Signal_t

Here, P_t is the closing price on day t, in US$ per share; N is the EMA period; and α is its weighting factor. EMA_t(N) is the price EMA on day t. EMA_t(MACD, 9) applies the same EMA calculation to the MACD line’s values, not to closing prices. The MACD line, signal line and histogram are all in US$ per share. A charting service must initialize each EMA from earlier observations, so a calculation cannot be reconstructed from one day’s price alone.

When the MACD line crosses above the signal line, the histogram moves above zero. A crossover below moves it below zero. Separately, MACD crosses zero when the 12-period and 26-period price EMAs become equal and then change order. These are descriptions of historical price calculations, not instructions to trade.

Worked example

Suppose a hypothetical stock has enough earlier daily observations to initialize all three EMAs. At the end of a trading day:

  1. Its 12-period price EMA is US$102 per share, and its 26-period price EMA is US$100 per share.
  2. The MACD line is US$102 − US$100 = +US$2 per share.
  3. Suppose the already-initialized 9-period EMA of the MACD line is +US$1.50 per share. That is the signal line.
  4. The histogram is US$2 − US$1.50 = +US$0.50 per share.

This snapshot shows the faster price EMA above the slower one and MACD above its signal line. It does not establish that a crossover occurred that day: identifying one requires the previous day’s values. Nor does a positive histogram establish what will happen next.

Why it matters before you trade

MACD can provide context for a price trend when reviewing a proposed stock trade. A pre-trade check asks additional questions that MACD does not answer: How large is the proposed order relative to daily volume? What are the estimated spread and market impact? What volatility and portfolio concentration would the trade introduce? A price-based indicator and an execution assessment address different risks.

MACD is calculated from past prices, and EMA smoothing introduces lag. Signals may reverse quickly when prices fluctuate without a sustained trend. Settings and chart intervals also matter: daily MACD and hourly MACD use different observations, even if both display 12, 26 and 9.

How PreTrAIde uses it

PreTrAIde’s product facts do not state that it calculates or uses MACD. Its pre-trade analysis is not chart-pattern technical analysis. Instead, a user specifies a stock basket with sides, quantities and execution conditions before placing an order. PreTrAIde assesses factors including estimated spread, participation in daily volume, market impact and daily volatility, then provides decision-support verdicts and reasoning. Those assessments can complement a separate review of MACD, but a PreTrAIde verdict is not a MACD signal or an investment recommendation.

Common mistakes

  • Treating a signal-line crossover as a reliable price forecast. It records a change in calculated momentum, not a guaranteed outcome.
  • Confusing a zero-line crossover with a signal-line crossover. They compare different quantities.
  • Comparing raw MACD values across stocks at very different prices as though the values were percentages.
  • Assuming the histogram’s positive value means momentum is increasing. It may remain positive while shrinking.
  • Ignoring spread, order size and liquidity because the chart looks favorable. MACD does not estimate execution costs.

Frequently asked questions

What does a positive MACD mean?

The faster price EMA is above the slower price EMA. A positive MACD alone does not say whether it is above its signal line or whether the stock’s price will rise.

What is the difference between the MACD line and the signal line?

The MACD line is the difference between two price EMAs, commonly the 12- and 26-period EMAs. The signal line is commonly a 9-period EMA of the MACD line.

Does PreTrAIde use MACD to give its verdict?

PreTrAIde’s product facts do not state that it uses MACD. Its pre-trade analysis evaluates a proposed basket using factors that include liquidity, volatility and estimated execution costs; its verdicts are decision support, not recommendations.

Related terms

Technical analysis Technical analysis is the study of historical prices, trading volume and chart-derived indicators to describe market trends and patterns, without relying primarily on company financial statements. Moving average Moving average is the average of a stock’s prices over a rolling number of trading periods, used to smooth short-term fluctuations and describe its past price trend. Momentum Momentum is the tendency of a stock’s recent price direction to persist for a period, often measured by its return over a specified lookback window. Pre-trade analysis Pre-trade analysis is the assessment of a proposed stock order or basket before placement, estimating execution costs, liquidity and risk to inform the investor’s decision and execution approach. Transaction cost analysis (TCA) Transaction cost analysis (TCA) is the measurement or estimation of a trade’s execution costs against a defined price benchmark, including effects such as spread, market impact and fees.

Technical analysis

Mean reversion Relative strength index (RSI) Bollinger Bands Support and resistance Trend following Breakout Market sentiment analysis News trading All glossary terms →

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Educational content, not investment advice. PreTrAIde is analysis software, not a broker: it never executes orders, and its verdicts are decision support, not recommendations to buy or sell.