Richard D. Wyckoff was a famous trader in the early 20th century known for his analysis of volume, price trends, and sector rotation. He viewed the market as a "composite man" representing total investor behavior. Wyckoff developed principles of supply and demand, effort vs. result, and cause and effect to identify accumulation and distribution patterns. His methods focused on analyzing price and volume trends using bar charts, point and figure charts, and tracking relative sector performance to identify trading opportunities. Wyckoff's teachings emphasized understanding the psychological phases of markets and using indicators like volume and trendlines to recognize accumulation and distribution periods.