Gerald Appel

Gerald Appel developed the Moving Average Convergence/Divergence (MACD) indicator in 1979 as a tool for identifying changes in the strength, direction, momentum, and duration of a trend. MACD plots the difference between two exponential moving averages (typically 12-period and 26-period) as a histogram, combined with a signal line (typically a 9-period EMA of the MACD line). Crossovers of the MACD and signal line generate buy and sell signals, while divergences between MACD and price can indicate trend reversals. The indicator became one of the most widely adopted in technical analysis, appearing as a default indicator in virtually every charting platform from Bloomberg to mobile trading apps. Appel founded Signalert Corporation, a New York-based investment advisory firm that uses systematic quantitative methods for asset management. He also wrote several books on technical analysis and systematic trading strategies. The ubiquity of MACD in modern trading makes Appel one of the most influential figures in practical technical analysis, even if less famous than some of his contemporaries.