DEFINITION of 'Post-Modern Portfolio Theory - PMPT'
A portfolio optimization methodology that uses the downside risk of returns instead of the mean variance of investment returns used by modern portfolio theory. The difference lies in each theory's definition of risk, and how that risk influences expected returns. Post-Modern Portfolio Theory (PMPT) uses the standard deviation of negative returns as the measure of risk, while modern portfolio uses the standard deviation of all returns as a measure of risk.
BREAKING DOWN 'Post-Modern Portfolio Theory - PMPT'
The differences between risk, as defined by the standard deviation of returns, between the post-modern portfolio theory and modern portfolio theory is the key factor in portfolio construction. Modern portfolio theory assumes that symetrical risk whereas PMPT assumes asymetrical risk. Downside risk captures what investors fear: having negative returns. After all, high positive returns are viewed as a good thing!