ContentsSummary 3Analysis of the situation 3Research on portfolio theory 4Variables that explain stock investment 5Factors to try to explain the phenomenon 7Conclusion 11References 12SummaryThe basis of this article is the analysis of the limited stock of families, phenomenon of market participation. The relevance of the issue is discussed through the perspective of finance theories with particular regard to model portfolio theory. Considering the point of view of one of the largest stock markets - the United States of America market - the phenomenon is first of all presented as deriving from behaviors linked to the ownership of stock securities. It is important to identify the characteristics of a typical American shareholder to draw further conclusions about the causes of the problem. In the following chapters, the variables used in recent research to try to explain the phenomenon are presented. Our article looks in more detail at the underlying risks faced by families and financial literacy. These were chosen by our team as particularly relevant and likely part of the main causes of limited household participation in the stock market in the United States. Situation Analysis It is known that a large number of families in the United States do not participate in stock markets. If we consider the historical models of this phenomenon, according to the panel study on income dynamics (PSID), which took into consideration a sample of 2998 families and took place in 1984, only a small percentage of families owned shares – 27, 6% (Mankiw, Zeldes, 1991). Among households with cash equivalent to $100,000 or more, only 47.7% owned stocks (Mankiw & Zeldes, 1991). Recent studies have estimated that even during the 1990s, when strong growth occurred in the US stock market...... middle of paper ......mouth.edu/~alusardi/Papers/Nether/LiteracyPaper_Lusardi. pdf on April 23, 2014The Federal Reserve Board. (2011). Limited market participation and asset prices under earnings management. Retrieved from: http://www.federalreserve.gov/pubs/ifdp/2011/1019/ifdp1019.htm on April 24, 2014Top Universities. (2012). How much does it cost to study in the United States? Retrieved from: http://www.topuniversities.com/student-info/student-finance/how-much-does-it-cost-study-us on April 23, 2014Wike, R., Holzwart, K. (2008). Where trust is high, crime and corruption are low. RewResearch Project on Global Attitudes. Retrieved from: http://www.pewglobal.org/2008/04/15/where-trust-is-high-crime-and-corruption-are-low/ on April 24, 2014 Global Stock Markets. (2012). List of stock exchanges around the world. Retrieved from: http://www.world-stock-exchanges.net/ on April 23 2014