Since the advent of modern portfolio theory more than half a century ago,1 investors and industry practitioners have concentrated on risk and return above nearly everything else.
The prescription is simple: pursue investments that offer the highest reward for a given level of risk (commonly expressed as a measure of volatility) or, conversely, that incur the lowest risk for a given level of return. Within this paradigm, metrics such as the Sharpe ratio2 and information ratio 3 have become common tools for constructing asset allocations and evaluating portfolio performance. At a high level, they distill return and risk into a single number.
But such metrics share an important limitation: They are inherently two-dimensional.
Investors are much more complex with multiple — often competing — and evolving needs. Risk and return are important, but so are things like income, inflation protection and preservation of capital during times of market stress. In addition, the relative importance of these objectives typically changes over the course of an investor’s lifetime. Focusing too narrowly on traditional optimization metrics, using just two dimensions, might mean missing what matters most to investors.
Recognizing that one size does not fit all, investment managers have sought to refine their asset allocation approaches to incorporate a broader perspective. One critique of traditional optimization approaches is their sensitivity to input estimations, which can dramatically impact an investor’s portfolio. Some asset managers have sought to address this and other limitations by applying a strong understanding of investor needs within multi-objective optimization models.
Multi-objective optimization examines multiple potential portfolios along multiple dimensions, as represented by various quantitative success metrics. An optimized portfolio can collectively deliver the most exposure to desired success metrics, which, in turn, can maximize exposure to the various real-world objectives associated with those metrics. Compared to a suboptimal portfolio, an optimized portfolio could, for example, have higher expected portfolio yield, higher expected return and lower expected volatility.
We believe that by taking a broader view of an investor’s goals, multi-objective optimization can offer managers a more nuanced approach to portfolio construction that can better address diverse objectives. Our approach combines deep research into investor personas, simulation modeling and robust quantitative methods to inform portfolio design. This is one element of our overall asset allocation process.
In the paper linked below, we take a closer look at the multi-objective optimization approach.
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1 Markowitz, Harry. “Portfolio Selection,” The Journal of Finance, March 1952.
2 Sharpe ratio is calculated by using standard deviation and excess return to determine reward per unit of risk. The higher the Sharpe ratio, the better the portfolio’s historical risk-adjusted performance.
3 Information ratio measures portfolio returns beyond the returns of a benchmark (or index) compared to the volatility of those returns.
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