Journal of International Business Research and Marketing
Volume 6, Issue 4, May 2021, pages 19-28
Strategic Asset Allocation in the Times of Financialized Commodity Markets
Poznań University of Economics, Poland
Abstract: The paper concentrates on the benefits of passive commodity investments in the context of the phenomenon of financialization. I investigate the implications of increase in the correlation between equity and commodity investments for commodity investors. The paper is composed of several parts. First, I describe the attributes of commodity investments and their benefits in the portfolio optimization. Second, I define the phenomenon of the finanzialization and develop my research hypothesis. Third, the section includes a description of data sources, research methods employed. Next, I present the results of the empirical analysis. I simulate the mean-variance spanning tests to examine the benefits of commodity investments before and after accounting for the impact of financialization. I proceed separate analysis for pre- and post-financialization period. The empirical research is based on asset classes’ returns and other related variables from years 1991-2012. The performed research indicates that the market financialization may have significant implications for commodity investors. Because of the increase in correlations, the inclusion of the commodity futures in the traditional stock-bond portfolio appears to be no longer reasonable.
Keywords: Commodities, Financialization, Mean-variance spanning, Portfolio optimization
The commodity futures once seemed to be a bit of a holy grail of the stock market. Almost a decade ago a few influencing papers documented that commodity investment are able to increase the portfolio expected return and while at the same time decreasing its risk. The publications were quickly followed by an explosion of various commodity investment vehicles and a huge inflow of money into the commodity markets. This process was later described as the “financialization” (Domanski and Heath, 2007). From this time on, the landscape of the commodity markets has changed profoundly. From the market of refineries, mines and farmers, which it once was, it became a market of hedge funds, exchange traded funds and commodity advisors.
It is still under discussion how the financialization affected the commodity markets. Some researchers suppose, that it underwent a deep and structural change. The financial literature usually indicates emerging of price bubbles (Masters, 2008; Gilbert, 2009; 2010; Einloth, 2009), increased correlation among commodities and with other asset classes (TDR, 2009; Tank and Xiong, 2010; Silvennoinen and Thorp, 2009) and changes in term structure of commodity markets (Schindler, 2007; Mayer, 2010; Tang and Xiong, 2010; Vdovenko, 2013; Brunetti and Reiffen, 2011).
As the phenomenon of the financialization is relatively new, we still do not have firm answers if and how it did change the commodity markets. Additionally, what is the most important from the investors’ perspective, we do not know, how it affected the investment conditions and opportunities in the commodity markets. This paper aims to investigate a single aspect financialization’s consequences – the increase in correlation with the equity market – and assess its implications for the commodity investors. The analysis is performed from the point of view of a traditional US dollar stock and bond investor. In other words, what I try to achieve is to find an answer to a question, whether after accounting for the changes in the term structure due to the financialization, it still makes sense to invest in commodities.
The paper is composed of several parts. First, I describe the characteristics of commodity investments. I also review the existing literature referring to the benefits of commodity investments. Second, I define the phenomenon of the finanzialization and develop my research hypothesis1. The third section includes description of the research methods employed and the data sources. Next, I present the results of the empirical analysis, which consists of two main stages. In the first stage, I perform the correlation analysis, to assess the impact of financialization on the commodity markets. In the second stage, I simulate mean-variance spanning tests to examine the benefits of commodity investments after accounting for the impact of financialization. The empirical research is based on asset classes’ returns and other related variables from years 1990-2012. Finally, the paper ends with the concluding remarks and indication of some areas for further research.
2. Commodities as an Investment
One of the key distinctions of commodities as an asset class is that there is no single way an investor can obtain exposure to them. In practise, there are three basic methods (Idzorek, 2007): direct physical purchase, commodity related stocks, commodity futures.
Each way of the exposures above has different risk and return characteristics. Physical investment is simply not very practical. Some commodities (particularly cattle and agricultural commodities) tend to perish quickly. Even those who do not perish, demand complicated storage and transportation. Actually, the only exceptions are precious metals, like gold or silver. Besides them, direct physical investment is fairly rare.
Commodity related stocks seem rather a part of a broader asset class of equities than commodities. They provide exposure to business skills of managers and specific factors related to companies, which in many cases may even hedge out their equity exposure. Therefore, some analysis indicate that commodity-related stocks tend to be stronger correlated with equities rather than with commodities (Zaremba, 2011). Gorton and Rouwenhorst (2006) build commodity stocks portfolio based on SIC codes and investigate its behaviour during 41 years period. The correlation to a commodity futures index is 0.40, while in case of S&P500 it is 0,57. Moreover, it appears that commodity stocks not only resemble rather equities than commodities, but also deliver lower rates of return and it is not very clear if they are an efficient inflation hedge (Gorton and Rouwenhorst, 2006). Many authors conclude that the portfolio of commodity related stocks is not a satisfactory way to gain exposure to commodities.
The third method, widely recognized as the most appropriate, is a direct investment in a portfolio of commodity futures. It can be done either by hiring a professional portfolio manager (CTA), who will actively manage the portfolio (managed futures) or by taking a passive long position in a commodity index. Furtheron, I will concentrate on the second way, as it is free from influence of active investment strategies.
The passive index investment is basically a purchase of a fully collaterized commodity futures portfolio, which are systematically rolled when (or before) they mature. The previous research in the field indicates numerous traits of such investments which make them particularly interesting for traditional equity and bond investors: positive skewness of the returns’ distribution (Deaton and Laroque, 1992; Armstead and Venkatraman, 2007), returns’ mean reversion properties, (Sorensen, 2002), hedging properties against inflation (Bodie, 1983; Gorton and Rouwenhorst, 2006; Froot, 1995; Till and Eagleeye, 2003a; Till and Eagleeye, 2003b; Akey, 2007), long-term positive risk premium (Till, 2007a; 2007b; 2007c), and low correlation with traditional asset classes, like stocks or bonds (Ankrim and Hensel, 1993; Becker and Finnerty, 1994; Kaplan and Lummer, 1998; Anson, 1999; Abanomey and Mathur, 2001; Georgiev, 2001; Gorton and Rouwenhorst, 2006).
The two previously mentioned characteristics – low correlation and long-term risk premium, which is not fully explained by the behaviour of other asset classes – make commodity futures particularly attractive for the strategic asset allocation. This issue has been in the scope of interest of researchers since the ‘70s in the twentieth century (Till, 2007a), so the literature in the field is relatively rich. The papers below are presented in chronological order.
The initial research focuses on the agricultural market in the USA and do not deliver promising results. Dusak, who in 1973 (Dusak, 1973) analyses listings of singular commodities in years 1962-67, is not able to confirm existence of the positive risk premium. The breakthrough in the field should be subscribed to Greer (1978), who treat commodities as an asset class. Greer shows that a risk associated with commodity investment may be effectively reduced by a full collateralization. Using a price index from years 1960-76 Greer documents that commodity investment performs better than equities, particularly by delivering higher returns with lower drawdowns than equities. Bodie and Rosansky, in their frequently cited paper from 1980 (Bodie and Rosansky, 1980), argue that commodity futures deliver the positive risk premium. They confirmed that the risk premiums was present in 22 out of 23 analysed markets in years 1950-73, however the statistical significance is rather weak. The reason is probably that the relatively high volatility of single futures, so Bodie and Rosansky performe also similar computations for a commodity index, which provided statistically significant rates of return. Similar results are later delivered by Bodie (1983), Carter et al. (1983), Chang (1985) and Fama and French (1987). Bessembinder (1992) notices that the presence and size of risk premium is dependent on the term structure, and Bjornson and Carter (1997) observed that the premium is correlated with macroeconomic factors: economic activity, inflation and interest rates. The higher risk premiums were historically usually observed when the interest rates were downward sloping, while the downward sloping interest rate curve coincided with the lower premiums. The research of Chong and Miffre (2006) reaches similar conclusions. Kaplan and Lummer (1998) concentrate on fully collateralized investments in S&P GSCI index and finds that the index investment historically achieved higher returns than equities, but at higher risk. The returns in the commodity markets are also in the scope of interest of Greer (2000), Till (2000a; 2000b) and Dunsby et al. (2008).
The more recent research on commodities’ risk premium emphasize the difference between premiums delivered by indices and by single commodities. Garcia and Leuthold (2004) confirmed the risk premium for an index in years 1982-2004, but reached equivocal conclusions concerning single future. Anson (2006) calculated that commodity portfolios achieved higher returns than bonds and equities in years 1970-2000, but at slightly higher risk. Erb and Harver (2006a) conclude that a confirmation or rejection of the risk premium hypothesis is highly dependent on research data and methodology. An important breakthrough happened in 2004, when a working paper of Gorton and Rouwenhorst was first time published. The article entitled “Facts and Fantasies about Commodity Futures” (Gorton and Rouwenhorst, 2006) is widely recognised as a birth of commodities as an asset class (Rogers, 2007; Authers, 2010). Gorton and Rouwenhorst find the statistically valid risk premium for a 36-commodities index in years 1959-2004. The portfolio performed slightly better than equities, particularly in the risk terms. On the other hand, they are unable to confirm statistically significant rates of return in single markets. The most of later papers confirms the findings of Gorton and Rouwenhorst. Kat and Oomen (2007a) do not prove risk premium for a broad spectrum of 42 commodities in years 1965-2005, and Scherer and He (2008) document risk premiums in years 1989-2006 for Deutsche Bank indices, but not for their constituents. Long-term index returns are also indicated by Hafner and Heiden (2008) in their analysis of years 1991–2006, Fuss et al. (2008) in the analysis of years 2001–2006, and Shore (2008), who observe the S&P GSCI index in years 1969–2006. Positive rates of return higher than these of stocks and bond are also documented by Nijman and Swinkels (2008), but the authors notice, that the volatility was historically higher than in case of the traditional asset classes. The risk premiums in commodity markets are also analysed by Gorton et al. (2012).
Another important field in the commodity research is the diversification properties and their benefits in portfolio context. Probably the first scientific analysis of this kind is performed by Greer in 1978. In his pioneer work (Greer, 1978) Greer proves, that the rebalanced portfolio of commodities, stocks and bonds delivers more stable and higher rates of return than pure bond-stock portfolio. Bodie and Rosansky (1980) notice, than allocation of 40% of portfolio to commodity future decreases risk while simultaneously increasing expected returns. Similar conclusions concerning benefits of commodity investing, are later reached by Jaffe (1989), Satyanarayan and Varangis (1994), Frood (1995), Kaplan and Lummer (1998) Fortenberry and Houser (1990), Jensen et al. (2000), Woodard et al. (2006) ,Anson (2006). Idzorek (2006) in calculations performed for Ibbotson Associates proves that commodities are weakly correlated witch stocks and bonds, because they are correlated to inflation, which is not true in case of stocks and bonds. Kat and Oomen (2007a) present that allocation of a part of portfolio to GSCI improves the portfolio’s Sharpe ratio, and Woodard (2008) documents that commodities in years 1989-2006 delivered positive risk premium, which could not be explained by returns of stocks or bonds. The shift in efficient frontier due to commodity allocation was indicated also by Scherer and He (2008) and Shore (2008). Finally, a paper of Heidon and Demidova-Manzel (2008) is one of the most interesting among the newest research. Both authors analyse return patterns of portfolio made of equities, sovereign and corporate bonds and real estate in years 1973-97, and conclude that investors should allocate between 5% to 36% proc. of their portfolio to commodities. Among the most recent researches, the benefits of commodities in the context of strategic asset allocation were also documented by Doeswijk et al. (2012) and Bekkers et al. (2012).
3. Market Financialization
Recent years brought a massive influx of money into commodity related products. It is said that at least 100 bilion dollars moved into commodity futures markets during years 2004-08 (Irwin and Sanders, 2011). Trading volume increased dramatically, and the presence of financial investors was constantly increasing. According to CFTC, the share of open interest held by non-commercial market participants surged from 15% in the beginning 1990 to over 42% in the end of 2012. Domanski and Heath (2007) coined term the “financialization” to describe the growing presence and importance of financial institutions in the commodity markets. The changes doesn’t seem to be temporal, but rather structural (Irwin and Sanders, 2012).
It seems rather rational to suppose, that such profound changes could have somehow altered the way the commodity markets work. A lot of research has been done in this field. Recent papers pointed a few structural changes that could took place in the commodity markets as the result of financialization: emerging of price bubbles (Masters, 2008; Gilbert, 2009; 2010; Einloth, 2009), increased correlation among commodities and with other asset classes (TDR, 2009; Tang and Xiong, 2010; Silvennoinen and Thorp, 2009) and changes in term structure of commodity markets (Schindler, 2007; Mayer, 2010; Tang and Xiong, 2010; Vdovenko, 2013; Brunetti and Reiffen, 2011).
In this paper, I concentrate on a single particular aspect of the financialization: the increase in correlation with equities. Numerous publications on benefits of investing in commodities and their diversification properties triggered a surge in popularity of commodity-related investments among institutional investors: investment funds, retirement funds and university endowments. The phenomenon is nicely depicted by the famous example of the Harvard University Endowment (Faber and Richardson, 2009). The allocation to commodities in years 1995-2010 increase over twice. The result of the increased presence of financial investors in the commodity markets may be some rise in correlation with traditional asset classes and lower diversification properties, than it is often suggested in popular research (Büyüksahin et al., 2008; Chong and Miffre, 2008).
There are two primary mechanisms which may lead to the soar in correlation. The first of them functions at the strategic allocation level and the other on the tactical allocation level. When the increasing number of investors have similar investment portfolios allocated to stocks, bonds and commodities, and the investors try to keep more or less stable asset allocation structure, then the external shocks resulting in capital outflows will enforce selling of all the asset classes in the portfolio. On the other hand, the capital inflows will result in the bigger demand for all the asset classes (Kyle and Xiong, 2001). As the result, the external shocks affecting stocks will also affect commodities, so the correlation will rise. What is more, in many papers the commodities are described as an asset class which benefits from the economic growth (Strongin and Petch, 1995; 1996; Gorton and Rouwenhorst, 2006; Armstead and Venkatraman, 2007; Kat and Oomen, 2007a; 2007b). It this way, that makes them similar to equities, so the demand for equities may be somehow synchronized with the demand for commodities. It may be an additional factor contributing to the correlation.
Increased correlation is documented in the paper of Tang and Xiong (2010). Similar conclusion are drawn by Silvennoinen and Thorp (2009) which analysed correlations between 24 commodities an equity indices in the USA, Great Britain, Germany and France. The computations are based on weekly data from the period May 1990 – July 2009. The research indicates growing cointegration of various asset classes, even after accounting for various external factors, like changes in volatility. The increase in intra-asset class correlation is also investigated and documented in papers of Tang (2011), Inamura et. al. (2010), Oztek and Ocal (2013), Dwyer et al. and Bhardwaj and Dunsby (2013).
4. Data and Research Design
In the empirical analysis in this paper I try to investigate whether commodities as an asset class are still beneficial in a portfolio context after taking into account for the increase in the correlation. Therefore, I simulate mean-variance spanning tests with and without potential changes. The mean-variance spanning test is designed to verify whether inclusion of an asset class into portfolio results in expanding investor’s efficient frontier. The test was initially proposed by Huberman and Kendel (1987), and later developed by for example Ferson et al. (1993), DeSantis (1993) and Bekaert and Urias (1996). Additionally Jobson and Korkie (1988) as well as Chen and Knez (1996) showed, that such test could be used to asses investment performance, and DeRoon, Nijman and Werger (2001) proved, that the test may be used for non-marketable assets 2 . Finally, there are many examples of mean-variance spanning test performed in the context of the commodities.
Let K denotes the set of benchmark assets with rates of return R1t, and N are the tested assets with rates of return R2t. Then, the formal test (the notation of Kan and Zhou (2001)) based usually on an simple OLS regression looks as follows (Kooli, 2006):
where the null hypothesis of mean-variance spanning is that:
Where 0N is defined as N-element vector of zeros. Kooli (2006) notices, that the test may be divided into two stages. The first stage is the verification of the shift of the tangency portfolio. If the tangency portfolio is moved, than an investor is able to build better optimal portfolios composed of risk-free asset and the tangency portfolio. It is worth noticing, that the improvement in the tangency portfolio is actually the improvement in the Sharpe ratio.
The aim of the mean variance spanning test in this paper is to examine, whether inclusion of commodities expands the efficient frontier of traditional portfolio composed of stocks and bonds. The test is made from the perspective of an US investor, so it encompasses dollar denominated assets. The equities as an asset class are represented by Willshire 5000 Total Market and the proxy for US government bonds is Bloomberg/EFFAS US Government Bonds All 1+. The JP Morgan Commodity Curve Index is used as the commodity portfolio. There are now many indices available, however JPM CCI is chosen due to several reasons. Firstly, it is dated back to December 1989, so it represents relatively long time series. Secondly, it is calculated in total, excess and spot return convention. Thirdly, it avoids a common front-run bias, because it exposes an index investor to a full commodity curve. Fourthly, its constituents are weighted according to open interests, which seems to be a good representation of investors’ universe. Finally, it does not assume any sophisticated active portfolio allocation methods, that could distort the pure returns to commodities as an asset class. All the indices are calculated in a total return regime. Additionally, USD BBA 1-month Libor is used so as to calculate excess returns over the risk-free asset (interpreted as the risk premium). All the data comes from Bloomberg and encompasses time-series 12/31/1991-12/31/2012, so from the very beginning all three indices are calculated. I compute arithmetical rates of return on a monthly basis.
In this paper I test the mean-variance spanning in two ways: using traditional OLS regression and with help of Monte Carlo analysis. The details of both methods are described below.
Most of mean-variance spanning test are based on total rates of return. In such case, it is rational to assume, that expositions to various asset classes should sum up to 1. However, in this research, I use risk-premiums defined as excess returns over money market. The regression model looks as follows:
where Rit is the return on the examined asset class’ (commodities), ct denotes money-market return in month t, and Rkt is k-asset’s rate of return (stocks and bonds). If ά, as specified in the model above, turns out to be statistically different from and higher than 0, one can say, that i constitutes a distinct asset class that generates its own risk premium. However, if that does not hold true, than an investor can probably replicate i’s returns without bearing higher risk or losing some of return.
This method is consistent with remarks of Anson (2009) and Scherer and He (2008), and was used in the commodity market for instance by Nijman and Swinkels (2008). The risk premium approach appears to be reasonable due to at least three reasons. Firstly, it does not imply, that the betas need to sum up to 1. Missing allocation can be filled with cash, or negative cash in case of leverage. Secondly, it makes the graphical interpretation and further analysis easier, because the tangency line of the tangency portfolio comes out from the origin of the coordinate system. Finally, it seems more practical as it corresponds with employing futures contracts in order to gain exposition to particular asset classes.
The main problem with the asset traditional OLS regression in case of commodities is that the return distribution of commodities seems to be far from normal (Anson, 2009; Gorton and Rouwenhorst, 2006; Erb and Harvey, 2006). In consequence, due to skewed distributions and fat-tails, the standard deviation may underestimate the true risk level. The problem is further explored by Johaning et al. (2006). Some papers in the field suggest to take into account also higher moments in the proces of portfolio analysis (Arditti and Levy, 1975; Markowitz, 1952; Samuelson, 1970; Harvey, Liechty and Muller, 2004; Cvitanic, 2005; Fang and Lai, 1997; Dittmar, 2002).
Therefore, in the second way I test the mean-variance spanning. As the risk measure, I use the modified value at risk (MVάR) proposed by Favre and Galeano (2002):
where m denotes the mean return, s is the standard deviation, S is skewness, K is kurtosis, and zc is the number of standard deviations appropriate for the calculated VaR. The MVaR is analytical in its character, but thanks to VaR Cornish-Fisher expansion (Cornish and Fisher, 1937) it better approximates distributions different from normal. Using MVaR is consistent with investor’s approach, who prefer distributions with positive skewness and low kurtosis (Scott and Horvath, 1980; Pratt and Zeckhauser, 1987).
So in the second approach, I proceed the statistical analysis as follows. First, I resample 10 000 times the panel data encompassing four time-series of monthly arithmetical returns, which included JP Morgan Commodity Curve Total Return Index, Willshire 5000 Total Markets, Bloomberg/EFFAS US Government Bonds All 1+ and USD BBA 1-month Libor. Second, for each resampling, I compute three monthly risk-premiums’ time series, which are differences between asset class’ indices and preceding month-end’s Libor. Third, in each case I find the risk-return efficient frontier based on excess frontier for stocks and bonds the MVaR as the proxy for risk. Fourth, I add the commodities to the asset class’ universe and find the efficient frontiers for all the three asset classes. Fifth, I calculate the tangency portfolios’ Sharpe ratios4 for both efficient frontiers. It is worth noting, that in the case of the MVaR approach, it is actually a measure called modified Sharpe ratio, which was described by Bacon (2008, p. 102). Sixth, I compute the improvement in Sharpe ratios, as the difference between the values after and before the commodity inclusion. As I noted this before, in the case of excess return framework (or in other words: risk premium framework), the improvement in the maximum achievable Sharpe ratio is actually equal with the mean- variance intersection. So seventh, I calculated the percentage of resampled efficient frontiers (out of 20 000), which involved Sharpe ratio’s improvement. The percentage of the cases, in which the Sharpe ratios did not increased, is my p-value.
Finally, all the analysis above are performed for three time-frames. First, for the full research period 1991-2012. Second, for the period of the low correlation ending in December 2004. Third, for the high correlation period beginning in January 2005. The dates are chosen intentionally, as the year 2004 is a symbolic breakthrough, it was the year when “Facts and Fantasies about Commodity Futures” were published for the first time. Finally, it is important to point out that the average monthly returns in the sample subperiods were adjusted in order to equalize them with the full sample period. Thanks to this operation, the mean-variance simulation will emphasize the changes in the covariance matrix, while ignoring the changes in expected rates of return.
5. Empirical Results
Figure 1 represents the 5-year rolling correlation between monthly returns of equities and commoditises along with its volatility bounds. The computations are based on monthly returns. One can see, that the correlation was clearly increasing in the recent years.
Figure 1: The correlation between equity and commodity returns in years 1991-2012
Figure 2 depicts the shift of the efficient frontier because of inclusion of the commodities based on raw historical data 1991-2012.
Figure 2: Commodity investments and the shift of the efficient frontier: the years 1991-2012
The efficient frontiers are “pushed” upward and leftward after inclusion of the commodities both in the mean-variance approach and in the mean-MVar approach. This effect is even stronger in the pre-financialization period (Figure 3). If we look at the years 1991-2004, the expansion is actually more visible.
Figure 3: Commodity investments and the shift of the efficient frontier: the years 1991-2004
However, this conclusion does not entirely hold true after accounting for the impact of financialization. As one can see in the Figure 4, the commodities offer not much better better investment opportunities. The frontier is shifted only a little.
Figure 4: Commodity investments and the shift of the efficient frontier: the years 2005-2012
Table 1 presents the results of mean variance spanning test analysis using the regression approach described in the previous section.
Table 1: The mean-variance spanning test: the OLS approach
The symbols *, **, and *** denote the statistical significance at the 10%, 5% and 1% levels.
The results generally confirm, what can be concluded from the mean-variance approach graphical analysis. Before accounting for the impact of the financialization, the intercept was positive and statistically significant at 5% level. It even remains so, when we look at the entire analysed period. However, after accounting for the changes, the intercept is still positive, but not statistically significant at any reasonable level. In other word, the benefits of the commodity futures in the traditional stock-bond portfolio cannot be still confirmed.
The observations above are confirmed by the results of the Monte Carlo analysis. The Table 2 presents the results of the Monte Carlo simulations for the sample.
Table 2: P-values in the Monte Carlo approach
The distributions of Sharpe ratios increases indicate, that in both approaches (variance and MVaR) the maximum attainable Sharpe ratio is significantly increased. Only 7,4% in case of draws the Sharp ratio do not go up. The situation changes when I split the sample into the two subsamples. Although the benefits in portfolio optimization are strongly emphasized in the pre-2005 period (4%), this is definitely not true after taking account the impact of financialization. As we can see, in 22,2% of MVaR draws, the investor opportunity set is not improved. Summing up, it seems, that after taking into account the impact of financialization, one cannot firmly state, that in the risk-return framework it still make sense to invest some share of a stock-bond portfolio in commodities.
6. Conclusions and Areas for Further Research
In this paper I focus on the benefits of passive commodity investments in the context of financialization. The recent financial literature indicated that financialization could have impacted the conditions of passive commodity investments. Many areas of the influence were identified, for example a bubble behaviour, increased correlations and distortions of the term curve. One of the key fields of impact could be the increase of correlations between commodities and equities.
The increase of the correlation comes not without an impact on the question whether some part of an investment portfolio should be allocated to the commodities. The mean-variance spanning tests show that what was true 10 or 20 years ago, may not bet true right now. Because of the soaring correlations, the inclusion of the commodity futures in the traditional stock-bond portfolio appears to be no longer reasonable. In other words, due to the process of commodity markets’ financialization, the benefits of commodity investments in the portfolio context may not be valid anymore.
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