He is most famous for inventing [2] and developing the concept of "On-balance volume (OBV)".

[3] On balance volume is thus one tool of technical analysis that attempts to predict future prices of stocks, commodities, and other financial assets traded on financial markets for which historical price and volume information is available.

[4] Granville published a popular financial newsletter called The Granville Market Letter from 1963 until shortly before his death in 2013, appeared frequently on television programs such as CNBC, and gave seminars nationwide.

Granville was known as a great showman [7] who would emerge from a coffin at an investment conference, or appear to walk across water (at a swimming pool) when meeting clients.

According to Robert Shiller, Granville's market calls were said by major media sources to have caused large moves in the Dow Jones Industrial Average on April 22, 1980 (+4.05%) and on January 6, 1981 (a reported $25 billion loss).