1 The Story
The manager who turned two moving averages into a standard
Around 1977, Gerald Appel set out to build a momentum indicator that was readable, simple to maintain, and didn't whipsaw traders to death. The result — the MACD — is still everywhere four decades later.
Born June 2, 1933 in New York City, Appel earned a degree from Brooklyn College and a Master of Social Work from NYU before a long career in markets. In 1973 he founded Signalert Asset Management — which grew to manage over $550 million — and the newsletter Systems and Forecasts. He wrote numerous investment books and managed client money for more than 35 years before retiring in 2012; he died in 2020.1
2 The Big Idea
Moving Average Convergence/Divergence
A momentum tool built for real use
The MACD subtracts a slower moving average from a faster one, then plots a signal line and histogram of the difference.
Appel's design goals were explicit: readable, low-whipsaw, and simple to maintain by hand — which is much of why it endured.1
3 The Method & Contribution
How the MACD works
Convergence / divergence
The core line is the gap between a fast and a slow EMA — it grows as momentum accelerates and shrinks as it fades.1
The signal line
An EMA of the MACD line; crossings are the classic (and often over-traded) signal.1
The histogram
Later refined by Thomas Aspray — the bars between MACD and signal, showing momentum building or fading.2
Divergence
Price making a new high while MACD does not — a warning that momentum is thinning.1
4 See It On This Site
MACD, explained on this site
Go deeper
Our MACD deep dive walks through the construction, the signal/histogram, divergence, the retail misuses, and the honest evidence.
5 The Work
His key contribution in print
Technical Analysis: Power Tools for Active Investors
FT Press · 2005- A practical synthesis of his indicator work, including the MACD.
- Backed by Signalert's quantitative, risk-reduction approach.
6 Read More
Go deeper
§ Sources
- Gerald Appel — biography, MACD & Signalert — CMT Association; obituary, New York Times / Legacy (2020).
- MACD histogram — refinement attributed to Thomas Aspray (1986) — overview.