Focusing on One Stock in a Portfolio
by Kurt Box
Mental accounting occurs when investors mentally compartmentalize assets such as stocks, bonds, real estate or accounts. This causes investors to lose sight of the big picture and instead focus on each specific investment and feel pleasure or pain depending on a particular investment's or account's performance.
Source: http://www.investorguide.com/igu-article-1051-stock-strategies-investing-driving-you-crazy-maybe-its-because-you-already-are-part-3.html