DEFINITION of 'PostModern 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. PostModern 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.
INVESTOPEDIA EXPLAINS 'PostModern Portfolio Theory  PMPT'
The differences between risk, as defined by the standard deviation of returns, between the postmodern 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!

Standard Deviation
1. A measure of the dispersion of a set of data from its mean. ... 
Expected Return
The amount one would anticipate receiving on an investment that ... 
Volatility
1. A statistical measure of the dispersion of returns for a given ... 
Modern Portfolio Theory  MPT
A theory on how riskaverse investors can construct portfolios ... 
Return
The gain or loss of a security in a particular period. The return ... 
Risk
The chance that an investment's actual return will be different ...

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