While there are no shortage of limitations and no “right” answers, portfolio theory nonetheless remains, rightly, the bedrock of traditional multi-asset portfolio design.
In this series of articles, I look at some of the key topics explored in my book “How to Invest With Exchange Traded Funds” that also underpin the portfolio design work Elston does for discretionary managers and financial advisers.
Portfolio theory in a nutshell
Portfolio theory, in a nutshell, is a framework as to how to construct an “optimised” portfolio using a range of asset classes, such as Equities, Bonds, Alternatives (neither equities nor bonds) and Cash. An “optimised” portfolio has the highest unit of potential return per unit of risk (volatility) taken.
The aim of a multi-asset portfolio is to maximise expected portfolio returns for a given level of portfolio risk, on the basis that risk and reward are the flipside of the same coin.
The introduction of “Alternative” assets, that are not correlated with equities or bonds (so that one “zigs” when the other “zags”), helps diversify portfolios, like a stabilizer. Done properly, this can help reduce portfolio volatility to less than the sum of its parts.
Whilst the framework of Modern Portfolio Theory was coined by Nobel laureate Harry Markowitz in 1952, the key assumptions for portfolios theory – namely which asset classes, their returns, risk and correlations are, by their nature, just estimates.
So using portfolio theory as a guide to designing portfolios is only as good as the quality of the inputs assumptions selected by the user. And those assumptions are ever-changing. Furthermore, the constraints imposed when designing or optimising a portfolio will determine the end shape of the portfolio for any given optimisation. And those constraints are subjective to the designer.
So portfolio design is part art, part science, and part common sense.
Whilst there are no shortage of limitations and no “right” answers, portfolio theory nonetheless remains, rightly, the bedrock of traditional multi-asset portfolio design.
What differentiates multi-asset portfolios?
A portfolio’s asset allocation is the key determinant of portfolio outcomes and the main driver of portfolio risk and return. Ensuring the asset allocation is aligned to an appropriate risk-return objective is therefore essential. Getting and keeping the asset allocation on track for the given objectives and constraints is how portfolio managers – whether of model portfolios or of multi-asset funds – can add most value for their clients.
There are no “secrets” to asset allocation in portfolio management. It is perhaps one of the most well-studied and researched fields of finance.
Stripping all the theory down to its bare bones, there are, in my view, three key decisions when designing multi-asset portfolios:
Strategic allocation is expected to answer the key questions of what are a portfolio’s objectives, and what are its constraints.
The mix of assets is defined such as to maximise the probability of achieving those objectives, subject to any specified constraints.
Objectives can be, for example:
Strategic allocations should be reviewed possibly each year and certainly not less than every 5 years. This is because assumptions change over time, all the time.
Static vs Dynamic
One of the key considerations when it comes to managing an allocation is to whether to adopt a static or dynamic approach.
A strategy with a “static” allocation, means the portfolios is rebalanced periodically back to the original strategic weights. The frequency of rebalancing can depend on the degree of “drift” that is allowed, but constrained by the frictional costs involved in implementing the rebalancing.
A strategy with a “dynamic” approach, means the asset allocation of the portfolios changes over time, and adapts to changing market or economic conditions. Dynamic or Tactical allocation, can be either with return-enhancing objective or a risk-reducing objective or both, or optimised to some other portfolio risk or return objective such as income yield.
For very long-term investors, such as endowment funds, a broadly static allocation approach will do just fine. Where very long-term time horizons are involved, the cost of trading may not be worthwhile. As time horizons shorten, the importance of a dynamic approach becomes increasingly important. Put simply, if you were investing for 50 years, tactical tweaks around the strategic allocation, won’t make as big a difference as if you were investing for just 5 years. This is because risk (as defined by volatility) is different for different time frames, and is higher for shorter time periods, and lower for longer time periods. In a way this is also just common sense. If you are saving up funds to buy a house, you will invest those funds differently if you are planning to buy a house in 3 years or 30 years. Time matters so much as it impacts objectives and constraints, as well as risk and return.
Managers need to make implementation decisions as regards how they access particular asset classes or exposures – with direct securities, higher cost active/non-index funds, or lower cost passive/index funds and ETFs. Fund level due diligence as regards underlying holdings, concentrations, round-trip dealing costs and internal and external fund liquidity profiles are key in this respect. The choice between direct equities, higher cost active funds or lower cost index funds is a key one and is the subject of a later article.
Types of multi-asset strategy
There is a broad range of multi-asset strategies available to investors, whose relevance depends on the investor’s needs and preferences. To self-directed investors, these multi-asset portfolios are made easier to access and monitor through multi-asset funds, many of which are themselves constructed wholly or partly with index funds and/or ETFs.
We categorise multi-asset funds into the following groups (using our own naming conventions based on design: these do not exist as official “multi-asset sectors”, unfortunately):
Relative risk strategies target a percentage allocation to equities so the risk and return of the strategy is in consistent relative proportion the (ever-changing) risk and return of the equity markets. This is the most common approach to multi-asset strategies. Put differently, asset weights drive portfolio risk. Examples include Vanguard LifeStrategy, HSBC Global Strategy and other traditional multi-asset funds.
Target risk strategies target a specific volatility level or range. This means the percentage allocation to equities is constantly changing to preserve a target volatility band. Put differently, portfolio risk objectives drive asset weights. Examples of this approach include BlackRock MyMap funds.
Target return strategies target a specific return level in excess of a benchmark rate e.g. LIBOR, and take the required risk to get there. This is good in theory for return targeting, but results are not guaranteed. Examples of this approach include funds in the Target Absolute Return sector, such as ASI Global Absolute Return.
Target Date Funds adapt an asset allocation over time from higher risk to lower, expecting regular withdrawals after the target date. This type of strategy works as “ready-made” age-based fund whose risk profile changes over time. Examples of target date funds include Vanguard Target Retirement Funds, and the Architas BirthStar Target Date Funds (managed by AllianceBernstein)*.
Target income funds target an absolute level of income or a target distribution yield. Examples of this type of fund include JPMorgan Multi-Asset Income.
Target Term Funds
These exist in the US, but not the UK, and are a type of fund that work like a bond: you invest a capital amount at the beginning, receive a regular distribution, and then receive a capital payment at the end of the target term.
For self-directed investors, choosing the approach that aligns best to your needs and requirements, and then selecting a fund within that sub-sector that has potential to deliver on those objectives – at good value for money – is the key decision for building a robust investment strategy.
The (lack of) secrets
The secret is, there are no secrets. Good portfolio design is about informed common senses. It means focusing on what will deliver on portfolio objectives and making sure those objectives are clearly identifiable by investors.
Designing and building your own multi-asset portfolio is interesting and rewarding. Equally there are a range of ready-made options to chose from. The most important question is to consider to what extent a strategy is consistent with your own needs and requirements.
* Note: funds referenced do not represent an endorsement or personal recommendation. Disclosure: until 2015, Elston was involved in the design and development of this fund range, but now receives no commercial benefit from these funds.