Portfolio management is the process of assembling and overseeing a selection of investments in stocks, bonds, and other securities that meet a particular investor’s desired balance of risk and expected return. Efficient portfolio construction and management are critically important for building wealth over the long term, enabling investors to earn more over time than just putting money in an interest-bearing savings account while avoiding the risk of attempting to pick individual stocks and “beat the market.”
Most strategies for portfolio optimization are based in modern portfolio theory, which is founded on the insight that evaluations of risk and return should be made about an entire collection of assets, not just individual assets. Thus, portfolio optimization is pursued by combining assets with different risk profiles that balance each other out in aggregate and minimize the overall portfolio risk for a given expected return. Statistical analyses of variance in price movements and correlations between assets are relied upon to build this efficient diversified portfolio.
Other portfolio theories have emerged to remedy perceived flaws in modern portfolio theory, giving portfolio managers additional tools. For example, post-modern portfolio theory seeks to more aggressively minimize downside risks, claiming that modern portfolio theory fails to adequately distinguish between regular small losses and rarer but more dangerous catastrophic declines in the market. Behavioral finance has also critiqued conventional portfolio management strategies for failing to account for the role of cognitive biases of investors and the market at large.