Risk Parity an Alternative Approach to Asset Allocation
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FEATURE Risk Parity An Alternative Approach to Asset Allocation Alexander Pekker, PhD, CFA®, ASA, Meghan P. Elwell, JD, AIFA®, and Robert G. Smith III, CIMC®, AIF® ollowing the financial crisis of tors, traditional RP strategies fall short respectively, but a rather high Sharpe 2008, many members of the of required return targets and leveraged ratio, 0.86. In other words, while the investment management com- RP strategies do not provide enough portfolio is unlikely to meet the expected F munity, including Sage,intensified their potential benefits to outweigh their return target of many institutional inves- scrutiny of mean-variance optimization risks. Instead we advocate a liability- tors (say, 7 percent or higher), its effi- (MVO) and modern portfolio theory based approach that incorporates risk ciency, or “bang for the buck” (i.e., return (MPT) as the bedrock of asset alloca- budgeting, a key theme of RP, as well as per unit of risk, in excess of the risk-free tion (Elwell and Pekker 2010). Among tactical asset allocation. rate), is quite strong. various alternative approaches to asset How does this sample RP portfo- What is Risk Parity? allocation, risk parity (RP) has been in the lio compare with a sample MVO port- news lately (e.g., Nauman 2012; Summers As noted above, an RP portfolio is one folio? A sample MVO portfolio with a 2012), especially as some hedge funds, where risk, defined as standard deviation return target of 7 percent is shown in such as AQR, and large plan sponsors, of returns, is distributed evenly among table 2. Unlike the sample RP portfolio, such as the San Diego County Employees all potential asset classes;1 table 1 shows the MVO portfolio is heavily allocated Retirement Association, have advocated a sample (unleveraged) RP portfolio toward equities, and it has much higher its adoption. based on sample adjusted historical cap- risk and a much lower Sharpe ratio. In The traditional MVO approach con- ital market assumptions.2 Heavily tilted addition, unlike in the sample RP port- structs a portfolio that minimizes total toward fixed income, this portfolio has folio where each asset class is allocated expected risk, defined as standard devi- modest expected return and standard 25 percent of the risk, here, U.S. equities ation of returns, subject to a desired deviation, 5 percent and 5.2 percent, make up the largest portion of the assets return target. Because equities typi- cally have much higher expected returns TABLE 1: SAMPLE (UNLEVERAGED) RISK PARITY PORTFOLIO than other asset classes, they make up Contribution to Contribution to Weight (%) Return (%) Risk (%) the largest portion of an MVO portfolio; as a result (and because they also typi- U.S. Fixed Income 69% 55% 25% cally have higher risk than many other Global Equities 10% 15% 25% asset classes), equities also contribute U.S. Equities 12% 20% 25% the largest share of portfolio risk, often Alternatives 10% 11% 25% more than 80 percent. In contrast, RP Total 100% 100% 100% constructs a portfolio such that all asset Return 5.0% classes contribute equally to portfolio Risk 5.2% risk, with the return determined by this Sharpe Ratio 0.86 allocation. As a result, RP portfolios have a much larger allocation to fixed income TABLE 2: SAMPLE MEAN-VARIANCE OPTIMIZATION PORTFOLIO and a much lower allocation to equities Contribution to Contribution to than MVO portfolios. Not surprisingly, Weight (%) Return (%) Risk (%) then, RP portfolios generally have lower U.S. Fixed Income 28% 16% 1% risk and lower return than MVO portfo- Global Equities 10% 11% 14% lios, unless leverage is allowed. U.S. Equities 57% 69% 81% In this article, we address some of the Alternatives 5% 4% 4% key issues associated with RP strategies, Total 100% 100% 100% including efficiency, leverage, imple- Return 7.0% mentation, past performance, and the Risk 10.5% impact of rising interest rates. We con- clude that, for most institutional inves- Sharpe Ratio 0.62 July/August 2013 23 © 2013 Investment Management Consultants Association. Reprint with permission only. FEATURE Practical Considerations and constitute 81 percent of the risk. depends on a key assumption, namely Thus, the sample MVO portfolio, while that funds can be consistently borrowed The first consideration in implementing achieving the desired return target, is at a relatively stable low rate. If this RP is the same one that befalls MVO: more risky and less efficient than the assumption is violated to a high enough its reliance on asset risk and correla- sample RP portfolio. degree, RP is no longer as appealing. tions estimates, either ex post or ex ante, As noted above, despite its high Indeed, in reality the cost of leverage which may or may not be at all indica- Sharpe ratio, the sample RP portfolio is varies. Market volatility, the amount bor- tive of the future. Each provider of not very attractive to most institutional rowed, the low quality of the underlying a RP strategy will use different methods investors—its expected return is just collateral, and rising overall levels to determine these parameters too low. However, by introducing lever- of interest rates are all factors that are (e.g., indexes corresponding to asset age, RP can be adjusted to reach the likely to increase borrowing costs. In par- classes, observation-period length, required return target, making it more ticular, the impact of market volatility on observation frequency, potential incor- competitive with an MVO portfolio. leveraged RP portfolios cannot be under- poration of correlations, forward-look- estimated. In times of extreme market ing adjustments, etc.), leading to some Leverage and Its Risks stress (such as the financial crisis of nontrivial variations in asset allocations To bring the sample RP portfolio to a 2008), the cost of borrowing rises sharply between RP strategies. Indeed, it’s gen- return target of 7 percent while main- while liquidity generally plummets. In erally well-known that small variations taining the same equal risk decomposi- such an environment, asset returns fall in risk assumptions, including correla- tion among asset classes, leverage must far below borrowing costs, and the fund tions, probably the most elusive MPT be employed. Assuming that the cost of may have to sell assets (if it can, given assumption to estimate, can lead to borrowing is fixed at 1 percent (or 0.5 the illiquidity of the markets) at inoppor- large variations in optimal asset alloca- percent above cash), the required lever- tune prices to meet margin and collateral tion (e.g., Elwell and Pekker 2010). This age is 49 percent (1.49 × 5.2% – 0.49 × requirements. This lose-lose proposition, unfortunate and inescapable variation in 1.0% = 7.0%). As table 3 shows, relative while seemingly remote, is an important parameters is at the root of all asset to the sample unleveraged RP portfolio, risk to keep in mind whenever borrowing allocations based on MPT. the Sharpe ratio is slightly lower, 0.83 vs. is involved, especially at such a high level The second consideration in imple- 0.86, but it is still much higher than that (almost half of the assets). menting RP is rebalancing. Typically RP of the sample MVO portfolio; in addi- Leverage often comes with other portfolios are rebalanced monthly or tion, the volatility of the sample lever- risks and costs as well. For example, quarterly based on risk parameters aged RP portfolio, 7.8 percent, is much while government bonds can be lev- computed over rolling time periods lower than that of the MVO portfolio. eraged through bond futures (which (e.g., rolling three-year periods). Thus Clearly, with its return equal to are traded on an exchange and con- RP rebalancing is typically more fre- that of the MVO portfolio and a lower sequently have virtually no counter- quent and involves greater dollar risk and greater efficiency (i.e., higher party risk and little basis risk), leverag- amounts than traditional strategies, Sharpe ratio) than the sample MVO ing other asset classes potentially would leading to higher transaction costs. portfolio, the sample leveraged RP port- require some kind of swap, introducing Occasionally, rebalancing may be folio becomes more appealing to insti- counterparty risk, basis risk, and addi- impossible due to lack of liquidity asso- tutional investors. All this analysis tional implementation costs. ciated with some alternative assets (e.g., hedge funds with lock-up peri- TABLE 3: SAMPLE LEVERAGED RISK PARITY PORTFOLIO ods or illiquid real estate), thus unravel- Contribution to Contribution to ing (at least in part) the whole premise Weight (%) Return (%) Risk (%) of RP. Moreover, if RP involves multiple U.S. Fixed Income 102% 4.1% 25% asset managers (e.g., specialists by asset Global Equities 15% 1.1% 25% class), the coordination of leverage and U.S. Equities 18% 1.5% 25% rebalancing across asset classes may be Alternatives 15% 0.8% 25% particularly cumbersome. Leverage –49% –0.5% 0% Finally, in today’s low-interest-rate Total 100% 7.0% 100% environment, RP requires extra scrutiny because of its high allocation to fixed Return 7.0% income and, in the case of leveraged Risk 7.8% RP, borrowing costs, both of which are Sharpe Ratio 0.83 closely tied to interest rates. This consid- 24 Investments&Wealth MONITOR © 2013 Investment Management Consultants Association. Reprint with permission only. FEATURE eration once again reveals the key draw- FIGURE 1: RANGE OF 1-YEAR RETURNS FOR UNLEVERAGED RP, LEVERAGED back of using MPT to construct asset RP, AND MVO PORTFOLIOS, ASSUMING INTEREST RATES RISE BY 1 PERCENT allocations: It is based on long-term 25% risk/return assumptions, not on current market conditions, economic outlook, or expectations for interest-rate shifts (and their impacts on asset returns).