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You may not be as diversified as you think

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Are you diversified?


Diversification is the key element when managing a portfolio. If you want to smooth the ups and downs of individual assets, combine them in a basket. The less correlated those assets are, the steadier the basket’s performance.  

Implementing this simple concept effectively, however, is not easy. One major reason is that asset correlations change over time, both in magnitude and direction. For example, when interest rates fall, bond prices go up but stocks can go up or down, depending on whether investors think that lower rates as a stimulus for the economy, or that they are a sign that the economy is slowing down. Because the relationship between stocks and bonds changes over time, the “optimal” proportion of both in a portfolio changes as well.

It is very difficult to forecast changes in correlations. That’s why a common approach is to assume that they will remain constant – which is where the advice that a portfolio must contain a 60% stocks/40% bonds comes from. The assumption is that such pre-set allocation will be good enough to smooth volatility and produce positive results, even if at times it is not the “best” mix for achieving the sometimes opposite goals of maximizing returns and minimizing volatility.

Is it possible to obtain better results by actively managing a mix of assets instead of fixing it at some arbitrary level?

This question is sometimes dismissed out of hand because it sounds like asking whether it is a good idea to “time the market”, an activity that is generally thought to reduce portfolio returns. Indeed, many studies show that portfolio results tend to decline when trading activity increases. The reason behind this is not clear. Some studies blame transaction costs associated with more frequent buying and selling, while others blame behavioral biases – chasing winners; holding on to losers far too long; fear and greed, etc. that are absent when a portfolio is left alone. Regardless, it is not difficult to show how simple active strategies can outperform a passive approach.

For example, it is possible to improve returns over a simple 70% stock/30% bond strategy with the following rebalancing rule: if stocks outperform bonds in any six-month period, change the mix to 90% stocks/10% bonds for the following six months. Otherwise, change it to 50%/50%. In other words, give an extra 20% to the asset class that did better in the prior six months. This “momentum” rule clearly outperforms the “passive” allocation for any base mix of stocks and bonds –70%/30%, 20%/80%, or any other. 

Dynamic versus Static portfolio allocations

Notably, the rule only improves results starting in the early 1990s, making little difference over the “base” allocation before then. This is because there was a substantial change in the correlation between interest rates and stock returns that started around that time. This phenomenon became clear in hindsight, and many of the papers that describe it were published many years after the fact. An investor dedicated to building portfolios on the basis of responding dynamically to shorter-term correlation changes could have achieved higher returns much sooner.

It seems plausible that looking at diversification in more dynamic terms can yield better results, and in fact dynamic techniques have spread widely in the last few years. This approach has been at the center of our practice since we started managing clients’ portfolios, and we focus on developing, improving, and implementing these techniques for individual investors.

While simple strategies like the one described can be effective over the very long term, their benefits over much shorter periods may be less apparent. This is important, because the usual life of an individual's investment portfolio is often measured in years, not decades. One consequence of this is that for retirement portfolios controlling volatility becomes more important than maximizing returns. This is because pursuing higher returns exposes a portfolio to more risk, which can get in the way of protecting a savings portfolio so it can fund future living expenses. While a static allocation designed to reduce risk must reduce its expected returns, a dynamic allocation tries to find a way to capture more of the upside while keeping risk low..

The main goal of managing diversification dynamically is to provide a better trade-off between higher returns (more risk) and lower volatility (less risk) than a static portfolio mix. This is best achieved over the long term, since fixed allocations can, and do, outperform dynamic management over shorter periods. The process used to improve this trade-off is often a differentiating factor among portfolio managers who pursue the same goal.

What now?

We believe that our portfolio management process, focused on measuring risk, can be very effective at managing the trade-off between risk and returns. We implement this process for our clients, tailored for their specific circumstances, and we can also help you evaluate your current goals and establish an investment plan aiming at steady, long-term returns while managing downside risk. Please send us a request for a copy of a whitepaper describing our investment process, or contact us if you would like to know more about how Path Financial’s investment process can work for you. We’ll be happy to set up a confidential meeting to discuss your path to financial success. Read more