In 1952,…only 6.5 million Americans (4% of the U.S. population, or roughly 9.5% of households) owned any common stock — below the 1920s level of 15 to 20% of households and far below the 2007 figure of 49.1%. In 1952, approximately half (46%) of equity investors owned only one issue (ed. emphasis mine).
— Janice M. Traflet, A Nation of Small Shareholders (Baltimore: The Johns Hopkins University Press, 2013), pp. 4–5.