metadata: authors: 0: author: Arezki,Rabah
1: author: Islam,Asif Mohammed
2: author: Rota-Graziosi,Gregoire
count: World
docna: 0: docna: Taming Private Leviathans : Regulation
            versus Taxation
docty: Policy Research Working Paper
subtopic: Energy and Natural Resources,Coastal and Marine Resources,Food Security,Oil Refining & Gas Industry,Public Sector Economics,Public Finance Decentralization and
            Poverty Reduction,Macro-Fiscal Policy,Taxation & Subsidies,Economic Adjustment and Lending
teratopic: Energy,Water Resources,Agriculture,Industry,Public Sector Development,Macroeconomics and Economic Growth
abstracts: cdata!: This paper explores the interplay
            between concentration of wealth and policies, namely
            regulation and taxation. The paper exploits variation in
            exposure to international commodity prices. Using a global
            panel data set of the net worth of billionaires, the results
            point to a positive relationship between commodity prices
            and the concentration of wealth at the top. Regulation
            especially pertaining to competition is found to limit the
            effects of commodity price shocks on the concentration of
            wealth, while taxation has little effect. Moreover,
            commodity price shocks crowd out non-resource tax revenue,
            hence limiting the scope for income transfers and
            redistribution. The results are consistent with the primacy
            of ex ante interventions over ex post ones for addressing
            wealth inequality.
repnme: repnme: Taming Private Leviathans : Regulation
            versus Taxation
display_title: Taming Private Leviathans :
            Regulation versus Taxation
listing_relative_url: /research/2021/01/32790864/taming-private-leviathans-regulation-versus-taxation
topicv3: Agriculture and Food Security m1326205 435,Natural Resources m1326446 1979,Environment, Natural Resources and Blue
            Economy m1327391 566,Taxation m1327615 1121,Natural Gas m1583894 4712
publishtoextweb_dt: 2021-01-29T00:00:00Z
historic_topic: Energy,Water Resources,Agriculture,Industry,Public Sector Development,Macroeconomics and Economic Growth
origu: Office of the Chief Economist (MNACE)
no_of_pages: 38
author_keys: 0: author_key: 1596791
1: author_key: 950662
2: author_key: 1065539
model_extractions: Policy Research Working Paper 9531 Taming Private Leviatha Regulation versus Taxation _Rabah Arezki Asif Islam Grégoire Rota-Graziosi_ Middle East and North Africa Region Office of the Chief Economist January 2021
Policy Research Working Paper 9531

# **Abstract**

This paper explores the interplay between concentration of wealth and policies, namely regulation and taxation. The paper exploits variation in exposure to international commodity prices. Using a global panel data set of the net worth of billionaires, the results point to a positive relationship between commodity prices and the concentration of wealth at the top. Regulation especially pertaining to competition is found to limit the effects of commodity price shocks on the concentration of wealth, while taxation has little effect. Moreover, commodity price shocks crowd out non-resource tax revenue, hence limiting the scope for income transfers and redistribution. The results are consistent with the primacy of ex ante interventions over ex post ones for addressing wealth inequality.

This paper is a product of the Office of the Chief Economist, Middle East and North Africa Region. It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world. Policy Research Working Papers are also posted on the Web at http://www.worldbank.org/prwp. The authors may be contacted at aislam@worldbank.org.

_The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent._ Produced by the Research Support Team
# **Taming Private Leviathans:**

# **Regulation versus Taxation**

Rabah Arezki, Asif Islam and <mark>Grégoire Rota-Graziosi</mark> _JEL_ Classification : D31 ; D63 ; H26 ; H20 ; O13 Keywords: inequality; wealth concentration, competition, tax, natural resources, development _____________________________________________________________________________________ Rabah Arezki is the Chief Economist of the African Development Bank, a Senior Fellow at Harvard Kennedy School of Government and a Research Fellow at CERDI. Asif Islam is a Senior Economist in the Chief Economist Office of the Middle East and North Africa at the World Bank. <mark>Grégoire Rota-Graziosi is the Director of the Centre d'Etudes et de Recherches sur le Développement International (CERDI),</mark> Université Clermont Auvergne, CNRS, CERDI, F63000 Clermont-Ferrand <mark>. We thank Andrea Barone, Olivier Blanchard, Simeon Djankov, Daniel Lederman, Tarek Masoud and Lemma Senbet for excellent suggestions and comments.</mark> We acknowledge the support received from the Agence Nationale de la Recherche of the French government through the program “Investissements d’avenir” (ANR-10-LABX-14-01). The findings, interpretations, and conclusions expressed in this paper do not necessarily reflect the views of the CERDI, World Bank or the African Development Bank or the governments they represent. The CERDI, World Bank and the African Development Bank do not guarantee the accuracy of data included in this work.
“any contract... in restraint of trade” and “Every person who shall monopolize, or attempt to monopolize...shall be deemed guilty of a felony” – US Sherman Act (1890)

# **1. Introduction**

In the late 19th century in the United States, rising inequality, social tensions and oligarchy led the federal government to reinvent itself as a regulator. The Sherman Antitrust Act of 1890 is the foundational federal statute in the development of U.S. competition law.<sup>1</sup> At the time, the gilded age called for a forceful response by the federal government to curb the rising power of the so-called robber barons including Cornelius Vanderbilt, John D. Rockefeller and Andrew Carnegie. Fast forward to today, the global rise of a class of billionaires coupled with heightened social tensions raises important questions about what to do about top wealth and income inequality (Wu, 2018). Competition policies and antitrust laws combined with strong enforcement mechanisms have a potentially powerful role to play in shaping the structure of an economy and society over and beyond taxation and redistribution policies. Indeed, protected sectors, cartels or collusion limit the impetus for investment, innovation, and growth (see Aghion and Griffit hs , 2005). The present paper explores the interplay between top wealth and policies, namely regulation and taxation, exploiting variation in exposure to international commodity prices.

The rise of top income and wealth inequality over recent decades is a consistent pattern across the world (Piketty, 2014).<sup>2</sup> Initially the rise of top incomes was documented for the United States and France (Piketty and Saez, 2003; Piketty, 2003), followed by several other advanced economies (Atkinson et al., 2011). Studies on top incomes in developing economies are sparse due to data limitation, but several studies have documented top income trends in developing economies.<sup>3</sup> The rise of top incomes points to a number of concerns including significant welfare losses for workers and associated adverse political consequences (Alesina and Perotti, 1996; Bartels, 2008; Lansing and Markiewicz, 2016). Wealth concentration at the top also raises issues regarding policies including as to whether interventions should be _ex ante_ or _ex post_ ( <mark>Fleurbaey and Peragine, 2013;</mark> Hsu, 2014).

The jury is still out on what drives the rise of top incomes. The literature has identified several factors driving top income and wealth inequality, namely globalization, technology, labor market institutions, decline in competition and fiscal policy—or generally social norms regarding pay inequality (Ma and Ruzic, 2020; Piketty and Saez, 2003; Philippon, 2019; Aghion et al, 2019). Hsu (2014) argues that there are legal roots to top income inequalities which might explain the pervasive higher returns to capital compared to the rate of GDP growth. On the normative front, there is a heated debate on the best approach to address the rise in top incomes. The dominant approach is either to address institutional factors favoring the ability of top income earners to channel rents their way or to reduce the returns to rent seeking by increasing marginal rates of taxation on high incomes (Bivens and Mischel, 2013). More recently, a debate has been raging on the use of a wealth tax as an instrument to reduce top incomes (Saez and Zucman, 2019).<sup>4</sup>

> 1 The Sherman Act gave way to The Clayton Antitrust Act of 1914.

> 2 Notwithstanding the conceptual differences between income inequality and wealth inequality, the two terms are used interchangeably hereafter. In the present paper, we use a measure of wealth inequality. As such the focus of the paper is on latter. In practice, measures of income and wealth inequality are strongly correlated. What is more, data on top incomes using tax administration data are more readily available than top wealth.

> 3 For studies of wealth and income inequality in developing countries, see Banerjee and Piketty, 2005; Leigh and van der Eng, 2009; Freund, 2016; Lopez et al., 2016; and Assouad et al, 2018.

> 4 See the debate hosted by the Peterson Institute for International Economics:

<u>https://www.piie.com/events/combating-inequality-rethinking-policies-reduce-inequality-advanced-economies,</u> accessed May 16, 2020.

2
In this paper, we document that different institutional arrangements lead to a differentiated effect of (plausibly) exogenous commodity price fluctuations on top incomes.<sup>5</sup> To do so, we combine a global panel data set from Forbes magazine on billionaires’ net worth with an index of (country-specific) commodity terms of trade shocks. Commodity shocks are significant sources of macroeconomic variation but also have important sectoral implications that elucidate linkages with concentration of income at the top. Results show that commodity booms lead to top income concentration, and the effect is economically large. Figure 1(a) globally traces the patterns of commodity shocks and the log differences of billionaire net worth and shows that they co-move. Figure 1(b) replicates the same pattern for developed (left panel) and developing economies (right panel) and shows the positive relationship between commodity price shocks and top incomes stand, regardless of the level of development. This finding is robust to accounting for sector of activity as well as the individual characteristics of billionaires as captured by billionaire fixed effects. The evidence is also suggestive that competition policy weakens the relationship between commodity booms and top incomes, and tax policy has no effect. However, we do find that commodity booms tend to lower tax revenues in the economy, hence reducing the scope for income transfers and redistribution.

In addition to the literature on top incomes, this paper contributes to several strands of literature. Specifically, the paper also relates to the so-called “resource curse” literature. The latter has provided (mixed) empirical evidence that countries with large dependence on natural resources grow slower (see survey by Ross et al., 2015) and are also more unequal (Ross, 2001; Sokoloff and Engerman, 2000).<sup>6</sup> Importantly, Mehlum, et al (2006) provide evidence that the effect of natural resources on the economy depends on the quality of institutions. Furthermore, the type of natural resource matters, with hydrocarbon and mineral resources, categorized as “point source” resources, having a more detrimental impact on growth than “diffuse” resources such as agriculture (see Isham et al., 2005). We contribute to this literature by focusing on the top incomes as opposed to general income inequality while exploring the role of different policy/institutional frameworks. We also find that commodity price shocks emanating from point source resources lead to more top income concentration than shocks stemming from diffuse resources.

> 5 To the extent that commodity prices and stock markets co-move, changes in commodity prices also affect billionaires’ net worth through changes in stock market valuation. See Arezki, Loungani, van der Ploeg and Venables (2014) and Ing-haw Cheng and Wei Xiong (2014) for a discussion on the respective role of fundamentals and financialization in driving commodity price fluctuations.

> 6 For an early contribution to the resource curse literature, see Sachs and Warner, 2001.

3
**Figure 1a: Log Differences of Billionaire Net Worth and Commodity Shocks**

<!-- Start of picture text --> Global<br>0.4 0.015<br>0.01<br>0.2<br>0.005<br>0 0<br>2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018<br>-0.2 -0.005<br>-0.01<br>-0.4<br>-0.015<br>-0.6 -0.02<br>Years<br>Log difference of Billionaire Net Worth<br>Log difference of commodity Net Export Price Index (historic rolling weights)<br>Worth<br>Export Price Index<br>Log difference of Billionaire Net Log difference of commodity Net<br><!-- End of picture text -->

**Figure 1b: Log Differences of Billionaire Net Worth and Commodity Shocks – Developing vs Developed Economies**

<!-- Start of picture text --> Developed Economies Developing Economies<br>0.4 0.015 0.6 0.015<br>0.3 0.01 0.4 0.01<br>0.2<br>0.005<br>0.1 0.005 0.2<br>0 0<br>0<br>-0.1 0 -0.005<br>-0.005<br>-0.2 -0.01<br>-0.2<br>-0.3 -0.01 -0.015<br>-0.4 -0.4<br>-0.015 -0.02<br>-0.5<br>-0.6 -0.02 -0.6 -0.025<br>Log difference of Billionaire Net Worth Log difference of Billionaire Net Worth<br>Log difference of commodity Net Export Price Index (historic rolling weights) Log difference of commodity Net Export Price Index (historic rolling weights)<br>2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018<br>Log Difference of Billionaire Net Worth Log Difference of Billionaire Net Worth<br>Log Difference of Commodity Net Export Price Index Log Difference of Commodity Net Export Price Index<br><!-- End of picture text --> Sources: Forbes Magazine (2001 to 2018); Gruss et al. (2019).

Globalization has led to a significant decrease in the cost of international capital mobility. In turn, this has fueled intense tax competition, which offers multiple opportunities to shift profits to wealth in tax accommodating countries or tax havens. Any tax coordination at the international level is rendered difficult or nearly impossible (see Rota-Graziosi, 2019). This may explain why taxation appears less efficient than regulation to tame top wealth inequalities as in this paper. Alstadsæter et al. (2018) find that 10 percent of world wealth is held in tax havens and that this masks important heterogeneity. Andersen et al. (2017) find that around 15% of the windfall gains accruing to petroleum-producing countries with autocratic rulers is diverted to secret accounts. The emerging debate on curbing top incomes has centered around the wealth tax (Saez and Zucman, 2019). There is indeed a strong theoretical case for a wealth tax especially after calamities such as wars and pandemics, yet its implementation and effectiveness have been challenged. In this paper, we find empirically that both resource and non-resource taxation do not moderate the effect of commodity booms on top incomes.

4
Further, we find that commodity price shocks reduce non-resource taxes, both direct and indirect. Our findings relate to the volatility of public budgets due to commodity price volatility (Robinson et al., 2017) and the resource curse in terms of public finances (Borge et al., 2015). James (2015) establishes a negative relationship between resource and non-resource revenues as the expression of a crowding out effect between these sources of revenue in US states. Our findings further contribute to this literature by documenting that certain institutional arrangements can help curb the rise in top incomes.

The remainder of the paper is structured as follows. Section 2 presents the data. Section 3 describes the estimation strategy. Section 4 presents the main results and robustness checks. Section 5 presents additional results. Section 6 concludes.

# **2. Data**

This section presents the data used in the empirical investigation.

# _2.1 Top Incomes_

Data on billionaire net worth (in USD) are used to proxy for top incomes. The data are obtained from Forbes magazine’s updated database of billionaires (2001 to 2018). Billionaires are identified based on their first name, last name, and their profile in Forbes magazine. Information from Wikipedia is used to fill in missing information on billionaire characteristics such as country of citizenship. The number of billionaires in the sample rose from approximately 565 in 2001 to 2,208 in 2018. Forbes magazine’s billionaire database has been used in the literature to study wealth distribution (Piketty, 2014; Bagchi et al., 2016), the international mobility of billionaires (Sanandaji, 2014), the emergence of Russian billionaires (Treisman, 2016), and statistical regularities at the top end of the wealth distribution (Klass et al., 2006) among others. Summary statistics for the sample of analysis are provided in Table A1.

# _2.2 Commodity Windfalls_

Data on commodity price shocks are obtained from the IMF (Gruss and Kebhaj, 2019). The commodity terms of trade index is based on international prices of up to 45 individual commodities, constituting broad categories of energy, metals, food and beverages, and agricultural raw materials. We calculate commodity price shocks by taking the first differences of the log of the price index as shown in equation (1) below.

Where is the natural log of the real price of commodity _j_ in year _t_ . Ω represents the commodityand country-specific time-varying weights, which are based on three-year rolling average trade flows over jj,tt cc,jj,tt the previous three calendar years. Similar measures of commodity windfalls have been used by Arezki PP and Brückner (2012).<sup>7</sup>

> 7 We employ a similar measure to calculate specific commodity sub-indices. There are marginal differences in terms of weights, but the methodology is largely the same.

5
In addition, variables on resource rents are also used to proxy for commodity windfalls. The data on natural resource rents come from the Changing Wealth of Nations data set of the World Bank (2011) available from the World Bank’s World Development Indicators (WDI). Natural resource rents are defined as the difference between the unit price of resources and their unit cost of extraction, multiplied by the volume of resources extracted. Total natural resources rents are the sum of oil rents, natural gas rents, coal rents (hard and soft), mineral rents, and forest rents. The data have been widely utilized in the literature (Klomp and de Haan, 2016; Arezki and Gylfason, 2013). Summary statistics for the sample of analysis are provided in Table A1.

# _2.3 Tax Data_

Tax data are obtained from the UNU-WIDER ICTD government revenue data set (Prichard et al, 2014). The data set combines several sources of tax data compiled from IMF Article IV reports, thereby ensuring extensive coverage. These include IMF Government Finance Statistics (GFS), World Bank World Development Indicators (WDI), OECD Tax Statistics, OECD Revenue Statistics in Latin America dataset, CEPAL Tax Statistics, and the AEO African Fiscal Performance. The data set includes a separate category for resource tax revenues, in addition to several other tax breakdowns. Data are available from 1980 to 2017. Summary statistics for the sample of analysis are provided in Table A1.

# **3. Estimation Strategy**

In this section we present our empirical strategy.

To explore the effect of commodity price shocks on billionaire net worth, we estimate the following equation: L 0<sup>+ ββ</sup> 1<sup>D</sup> (2) ii,tt<sup>= αα</sup> cc,tt<sup>+ γγ</sup> ZZ<sup>DDLLIICCDDLLDDCC</sup> cc,tt<sup>+ ττ</sup> tt<sup>+ υυ</sup> ii<sup>+ εε</sup> ii,tt Where L LLIIL is the log of billionaire net worth in USD for individual<sup>DDIIDDLLDDPPD</sup> _i_ at time _t_ ; D is the log difference of the commodity price index in country _c_ , is a vector of country-level controls including structure and size of the economy. LLIIL is the year fixed effects and represents individual billionaire DDIIDDLLDDPPD fixed effects. As a robustness check, we estimate equation (2) using country fixed effects instead of DDLLIICCDDLLDDCC billionaire fixed effects. Alternatively, we also estimate equation (2) using resource rents in place of ττ υυ commodity price shocks.

Our identification strategy allows us to account for several endogeneity issues. The commodity price shock variables are plausibly exogenous considering most countries are price takers in most commodities they trade, hence limiting the simultaneity bias. We limit omitted variable bias in several ways. Billionaire fixed effects are used to account for time-invariant billionaire-specific and country-specific unobservables. This can include education, ability, as well as geographic location and main sector of activity if they do not vary over time. The year fixed effects capture common year shocks. We also include country-level covariates that capture the size and structure of the economy, that could be important predictors of billionaire net worth.

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# **4. Top Income Results**

In this section we present our main results.

# _4.1 Baseline_

Table 1 presents our baseline estimates of the effect of commodity price shocks on billionaire net worth. Column 1 provides the estimates accounting for country and year fixed effects. This yields a positive effect of commodity price shocks (booms) on billionaire net worth, statistically significant at the 1% level. However, the estimates may be susceptible to omitted variable bias given several individual-specific time invariant characteristics including inherent ability and family background that may be important predictors of billionaire net worth. In column (2) we replace country fixed effects with billionaire fixed effects to account for these factors. The magnitude of the coefficient drops but the main results remain – positive commodity price shocks increase billionaire net worth, statistically significant at the 1% level. In column 3 we account for the size of the economy, which is positively correlated with billionaire net worth, suggesting scale effects where the net worth of billionaires increases with the size of the economy. Taking the estimates in column 3, a one percentage point increase in the log difference of commodity prices results in a 38% increase billionaire net worth. However, a percentage point increase in the growth rate of commodity prices is a sizeable increase. Thus a 1% increase in commodity prices translates to a 0.004 percent increase in billionaire net worth. A one standard deviation increase in the log difference of commodity prices leads to a 1.3% increase in billionaire net worth, which is roughly 1.5% of the sample mean of billionaire net worth. In table 2 we employ a measure of resource rents as an alternative to commodity price shocks. The results are consistent – resource rents are positively related to billionaire net worth, statistically significant at the 1% level irrespective of whether the specification includes country or billionaire fixed effects. The drawback of this measure is that it is unlikely to be exogenous.

In table 3, we delve deeper into price sub-indices of specific groups of commodities. These commodity divisions include (i) hydrocarbons (crude, coal and natural gas) (ii) Metals and Minerals (base metals, precious metals, fertilizer) and (iii) Agriculture (raw materials), Food and Beverages. We find that hydrocarbons commodity price shocks (booms) are positively related with billionaire net worth, statistically significant at the 1% level, regardless of whether the specification includes country fixed effects (column 1) or billionaire fixed effects (columns 2 and 3). Positive agriculture, food, and beverage commodity price shocks are negatively related to billionaire net worth, statistically significant at the 1% level, regardless of whether the specification includes country fixed effects (column 1) or billionaire fixed effects (columns 2 and 3). In table A2 in the appendix, we explore even more refined breakdowns of the commodity price index. We find that crude oil price shocks (booms) are positively related with billionaire net worth, while positive food price shocks are negatively related to billionaire net worth, both findings statistically significant at the 1% level.

These results complement Isham et al. (2015) that finds countries with natural resources extracted for a narrow geographic region or economic base (point source natural resource) are predisposed to weakened institutional capacity. This may in turn limit the ability of governments to adequately tax top incomes. In contrast, economies with diffuse natural resources (livestock and agricultural produce) do not exhibit similar weak institutional capacity and have more robust growth recoveries. This is also consistent with the natural resource rents results as reported in table 4: billionaire net worth is positively correlated with point source natural resource rents such as oil and natural gas, mineral and coal rents, while negatively correlated with diffuse resources such as forest rents (statistically significant between 1% and 5%).

An alternative approach is to estimate the effect of economic growth on billionaire net worth using commodity price shocks as instruments. These findings are reported in table 5. Hydrocarbon commodity price shocks have a positive and statistically significant effect on economic growth, while price shocks 7
from metals, minerals, agriculture, food and beverages have a negative and statistically significant effect on economic growth. Economic growth is positively related to billionaire net worth, with the coefficient being statistically significant at the 1% level. These findings stand whether billionaire or country fixed effects are employed. The instruments reject under-identification. The instruments also pass the overidentification test, especially when billionaire fixed effects are used, indicating that the validity of the instruments cannot be rejected. The instruments are also strong, given that they pass the weak identification test, exceeding the Stock and Yogo critical values.

The findings thus far point to a plausible mechanism whereby top incomes increase in the face of growth or commodity terms of trade shocks. We test whether this is conditional on the degree of market contestability/competition and quality of institutions in the economy. We use the sample average of the control of corruption quality of governance indicator. This captures perceptions of the extent to which public power is exercised for private gain, including both petty and grand. We also use the sample averages of the World Economic Forum’s indicators on the intensity of location and market domination. The former measure considers the distortive effect of taxes and subsidies on competition, the extent of market dominance, and competition in services. The market dominance indicator measures perceptions of whether corporate activity is characterized by a few business groups or many firms. For all the indicators, higher values imply better governance/market contestability.

Table 6 reports the findings. All interactions between governance/competition and commodity price shocks have negative and statistically significant coefficients. The same results are found when the governance/competition variables are interacted with resource rents. The results indicate that in countries with more contestable markets and good governance, top incomes are less likely to increase as a result of positive commodity price shocks. These findings are consistent with Andersen et al. (2017) that finds that exogenous shocks in petroleum income increase hidden wealth in offshore accounts for economies where institutional checks and balances are weak.<sup>8</sup>

# _4.2 Robustness Checks_

_Sector of activity and structure of the economy_ The estimates provided thus far are based on parsimonious specifications. In the following, we explore the robustness of the baseline findings along several dimensions. First, the structure of the economy may be an important predictor of billionaire net worth. Second, the sector of billionaire activity may also matter, to the extent that it varies over time. In tables A3 and A4, we replicate tables 1 and 2 respectively with the inclusion of the share of manufacturing and agriculture as a percent of GDP as additional covariates. The sign, significance and magnitude are relatively unchanged for the commodity price shock and resource rents coefficients.

The Forbes magazine database does include data on the billionaire sector of activity that encompass about 57 sectors of activity. However, this variable is measured with error given a single billionaire can be involved across multiple sectors. Furthermore, the 57 sectors do not seem to be mutually exclusive. We therefore recategorize the 57 sectors into 6 broad categories (see table A7) that include: (a) Agriculture (b) Extractives (c) Manufacturing (d) Services (e) IT and (f) Others. In tables A5 and A6 we present the results for commodity price shocks and resource rents respectively, after accounting for sector fixed effects for the narrow 57 categories, and the broad 6 categories. Our main results are robust. Indeed, the magnitude, sign and significance of the coefficients are similar to our baseline estimates.

> 8 See Ross (2015) for a summary of the literature on the relationship between institutions and commodity booms.

8
# _Citizenship versus residency_

Finally, our findings are based on the billionaire country of citizenship. The choice is logical given that a billionaire may exert greater influence in the country of her or his citizenship. However, this may not always be the case, and billionaires may have greater influence in their place of residence. Furthermore, there is some ambiguity in the case of dual citizenship, with the database in some cases assigning the citizenship at birth. In 2001, 1.2 percent of billionaires in the sample were not residents in their country of citizenship. This grew to 9.3 percent in 2018. Thus, we reproduce our baseline results using billionaire residency instead of citizenship in table A8. Our main results are robust.

# **5. Additional Results**

In this section, we explore additional results related to tax policies and tax revenue mobilization following commodity price shocks.

# _Interaction with Taxes_

We investigate whether higher taxes lessen the positive effect of commodity shocks and natural resource rents on billionaire net worth. Countries with greater capacity to tax may be able to capture some of the windfalls from commodity booms by extracting revenues from top incomes. As reported in table 7, we find no such effects. The coefficient of the interaction terms between tax revenues and commodity price shocks is statistically insignificant. This remains the case if we interact commodity price shocks with resource taxes, or the ratio of indirect over direct taxes. The results are similar when using resource rents, bar one exception. The interaction between total resource rents and the ratio of indirect over direct taxes is positive and statistically significant, albeit at the 10% level. The implication may be that a tax structure that favors indirect taxes allows billionaires to gather a larger share of commodity windfalls.

# _Effects of Commodity Price Shocks on Taxes and Social Contributions_

The inability of taxes to lessen the effects of commodity price shocks on top incomes raises the question as to whether such shocks have a direct effect on taxes themselves. In Table 8 we regress tax revenues as a percentage of GDP (excluding revenues from resources) on the log differences of the commodity price index. We uncover a negative coefficient for commodity price shocks, statistically significant at the 1% level (column 1, table 7). These results are mirrored in table A9 using resource rents in place of commodity price shocks. Commodity price booms are associated with weakening non-resource tax capacity, which may explain why the effect of commodity price shocks on billionaire net worth is unaffected by the country's tax rates. Looking at subcomponents of the commodity price indices, hydrocarbons and agriculture, food and beverages have negative coefficients, statistically significant at the 10% level (column 2, table 8). Breaking down these sub-categories even further, base metals, coal and natural gas price shocks (commodity booms) have negative coefficients, statistically significant at least at the 10% level (column 3, table 8). The crude oil price shock variable has a negative effect but is statistically insignificant. The findings for the breakdown of resource rents are provided in column 2 of Table A9. Oil and natural gas rents are negatively related to tax revenues, the coefficient being statistically significant at the 1% level. This provides mixed evidence as to whether point source resource booms as opposed to diffused resource booms may weaken the tax capacity of economies.

We unpack these findings further by investigating the effects of commodity price shocks on the composition of tax revenues (as a share of GDP), as reported in table A10. The log difference of the commodity price index is negatively related to direct and indirect taxes, statistically significant at the 1% and 5% level 9
respectively. There is a positive relationship with resource tax revenues, but the coefficient is not statistically significant. Table A11 replicates the findings of Table A10 using resource rents in place of commodity price shocks. Total resource rents are positively correlated with resource tax revenues, as expected, the coefficient being statistically significant at the 10% level. Resource rents are also negatively correlated with indirect taxes, with the coefficient being statistically significant at the 1% level. However, there is no statistically significant relationship with direct taxes. The evidence points to commodity price booms lowering non-resource tax revenues across the board, whether direct or indirect. However, the evidence is weaker with regards to resource rents and direct taxes.

An additional result we explore is whether commodity price shocks and resource rents have any effects on social contributions (as a % of total revenue). Results are presented in table A12. The coefficient for the log differences of commodity prices is negative and statistically significant at the 1% level (column 1, table A12). We find similar findings for natural resource rents - the coefficient is negative and statistically significant at the 1% level (column 3, Table A12). There are barely any statistically significant results for the sub-price indices with the exception of metals and minerals with a negative coefficient that is statistically significant at the 10% level (column 2, table A12). However, the findings are stronger when using with resource rates with coefficients for oil and natural gas rents as well as mineral and coal rents being negative and statistically significant at the 5% level. The results are suggestive that commodity price booms are negatively related to social contributions.

# **6. Conclusion**

In this paper we explored the relationship between commodity booms and top incomes using billionaires’ net worth. Our main finding is that commodity booms increase billionaire net worth. We find that the type of resource matters – price shocks from point source resources such as hydrocarbons, where rents are more easily captured, are more likely to raise top incomes while price shocks from diffuse source resources are not. The positive relationship between commodity price shocks and top incomes is attenuated by a higher degree of competition in markets but is unaffected by taxes. In fact, we find that commodity price shocks tend to reduce the non-resource component of both direct and indirect taxes, hence limiting the scope for income transfers and redistribution. These findings contribute to the current policy debate on curbing the rise in top incomes that has been focused on wealth taxes as a possible instrument. While there is a strong rationale for a wealth tax, especially following various calamities, its implementation can be challenging considering the sophisticated tax avoidance of high net worth individuals. Our empirical finding highlighting the potency of competition policy is consistent with the primacy of _ex ante_ interventions over _ex post_ ones to address top income inequality.

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13
# **Table 1: Price Shocks and Billionaire Net Worth**

|**Model**|**Country and Year**<br>**Fixed Effects**|**Billionaire and Year**<br>**Fixed Effects**|**Billionaire and Year**<br>**Fixed Effects**|
|---|---|---|---|
|**Dependent Variable**|**Log of**|**Billionaire Net Worth (in B**|**illions)**|
||**(1)**|**(2)**|**(3)**|
|Log difference of commodity Net Export Price Index<br>(historic rolling weights)|0.622***|0.387***|0.380***|
||(0.187)|(0.148)|(0.146)|
|Log of GDP (constant 2010 US$)|||0.145***<br>(0.053)|
|Constant|0.888***|0.467***|-3.673**|
||(0.030)|(0.030)|(1.526)|
|Country Fixed Effects|YES|NO|NO|
|Billionaire Fixed effects|NO|YES|YES|
|Year Fixed Effects|YES|YES|YES|
|Number of observations|20,512|20,512|20,502|
|R2|0.064|0.285|0.289|
|Adjusted R2|0.060|0.284|0.289|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level

**<u>Table 2: Natural Resource Rents and Billionaire Net Worth</u>**

|**Model**|**Country and Year**<br>**Fixed Effects**|<br>**Billionaire and Year**<br>**Fixed Effects**|**Billionaire and Year Fixed**<br>**Effects**|
|---|---|---|---|
|**Dependent Variable**||**Log of Billionaire Net Worth**|**(in Billions)**|
||**(1)**|**(2)**|**(3)**|
|Total natural resources rents (% of GDP)|0.012***|0.014***|0.013***|
||(0.004)|(0.003)|(0.003)|
|Log of GDP (constant 2010 US$)|||0.087**<br>(0.038)|
|Constant|0.670***|0.451***|-2.037*|
||(0.082)|(0.030)|(1.091)|
|Country Fixed Effects|YES|NO|NO|
|Billionaire Fixed effects|NO|YES|YES|
|Year Fixed Effects|YES|YES|YES|
|Number of observations|18,382|18,382|18,375|
|R2|0.066|0.276|0.277|
|Adjusted R2|0.062|0.275|0.277|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level 14
# **Table 3: Disaggregated Commodity Price Shocks and Billionaire Net Worth**

|**Model**|**Country and**<br>**Year Fixed**<br>**Effects**|**Billionaire and Y**|**ear Fixed Effects**|
|---|---|---|---|
|**Dependent Variable**|**Log of Bil**|**lionaire Net Worth (**|**in Billions)**|
||**(1)**|**(2)**|**(3)**|
|Log Difference of Hydrocarbons Commodity Index|0.213***|0.226***|0.224***|
||(0.081)|(0.067)|(0.067)|
|Log Difference of Metals and Minerals Commodity Index|0.366*|0.062|0.046|
||(0.217)|(0.144)|(0.142)|
|Log Difference of Agriculture, Food, and Beverages Commodity Index|-0.574***|-0.701***|-0.692***|
||(0.184)|(0.146)|(0.147)|
|Log of GDP (constant 2010 US$)|||0.106**|
||||(0.047)|
|Constant|1.010***|0.545***|-2.479*|
||(0.054)|(0.028)|(1.335)|
|Country Fixed Effects|YES|NO|NO|
|Billionaire Fixed effects|NO|YES|YES|
|Year Fixed Effects|YES|YES|YES|
|Number of observations|14,431|14,431|14,431|
|R2|0.072|0.288|0.290|
|Adjusted R2|0.066|0.287|0.289|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level 15
**<u>Table 4: Disaggregated Resource Rents and Billionaire Net Worth</u>**

|**Model**|**Country and Year**<br>**Fixed Effects**|**Billionaire and Year**<br>**Fixed Effects**|**Billionaire and Year**<br>**Fixed Effects**|
|---|---|---|---|
|**Dependent Variable**|**Log of**|**Billionaire Net Worth (in B**|**illions)**|
||**(1)**|**(2)**|**(3)**|
|Oil and Natural Gas Rents (% of GDP)|0.011***|0.014***|0.012***|
||(0.004)|(0.003)|(0.003)|
|Mineral and Coal Rents (% of GDP)|0.024**|0.026**|0.028***|
||(0.009)|(0.010)|(0.010)|
|Forest rents (% of GDP)|-0.117**|-0.297***|-0.285***|
||(0.059)|(0.058)|(0.058)|
|Log of GDP (constant 2010 US$)|||0.089*<br>(0.046)|
|Constant|0.752***|0.494***|-2.046|
||(0.088)|(0.032)|(1.322)|
|Country Fixed Effects|YES|NO|NO|
|Billionaire Fixed effects|NO|YES|YES|
|Year Fixed Effects|YES|YES|YES|
|Number of observations|18,351|18,351|18,351|
|R2|0.066|0.281|0.282|
|Adjusted R2|0.061|0.280|0.282|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level 16
# **Table 5: Economic Growth and Billionaire Net Worth using Disaggregate Price Shocks as Instruments**

|**Outcome Variable**||**Billionaire**|**Net Worth**||
|---|---|---|---|---|
|**Model**|**IV Country a**|**nd Year FE**|**IV Billionair**|**e and Year FE**|
||**Second Stage**|**First Stage**|**Second**<br>**Stage **|**First Stage**|
|**Outcome Variable**|**Billionaire Net**<br>**Worth**|**Log**<br>**difference**<br>**GDP**|**Billionaire**<br>**Net Worth**|**Log**<br>**difference**<br>**GDP**|
||**(3)**|**(4)**|**(1)**|**(2)**|
|Log difference GDP|3.282***<br>(0.944)||4.088***<br>(0.837)||
|Log Difference of Hydrocarbons Commodity Index||0.052***<br>(0.004)||0.054***<br>(0.005)|
|Log Difference of Metals and Minerals Commodity Index||-0.041***<br>(0.013)||-0.045***<br>(0.013)|
|Log Difference of Agriculture, Food, and Beverages Commodity<br>Index||-0.176***<br>(0.019)||-0.161***<br>(0.020)|
|Underidentification test (p-value)|0.000||0.000||
|Weak identification test (F stat)|76.063||62.295||
|**Stock-Yogo weak ID test critical values:**|||||
|5% maximal IV relative bias|13.910||13.910||
|10% maximal IV relative bias|9.080||9.080||
|20% maximal IV relative bias|6.460||6.460||
|30% maximal IV relative bias|5.390||5.390||
|10% maximal IV size|22.300||22.300||
|15% maximal IV size|12.830||12.830||
|20% maximal IV size|9.540||9.540||
|25% maximal IV size|7.800||7.800||
|Hansen J statistic (overidentification test, p-value)|0.040||0.253||
|Billionaire Fixed Effects|NO|NO|YES|YES|
|Country Fixed Effects|YES|YES|NO|NO|
|Year Fixed Effects|YES|YES|YES|YES|
|Number of observations|14,431|14,431|13,835|13,835|

note: *** p<0.01, ** p<0.05, * p<0.1, robust standard errors clustered at the billionaire level 17
# **Table 6: Interaction with Institutions**

|**Model**||**Bill**|**ionaire and**|**Year Fixed E**|**ffects**||
|---|---|---|---|---|---|---|
|**Dependent Variable**||**Log of**|**Billionaire N**|**et Worth (in**|**Billions)**||
||**(1)**|**(2)**|**(3)**|**(4)**|**(5)**|**(6)**|
|Log Difference of Commodity Net Export Price Index x WEF<br>Local Competition (0717)|-0.758**<br>(0.361)||||||
|Log Difference of Commodity Net Export Price Index x WEF<br>Market Dominance (0717)||-0.488*<br>(0.253)|||||
|Log Difference of Commodity Net Export Price Index x WGI<br>Control of Corruption (0118)|||-0.326**<br>(0.153)||||
|Total natural resources rents x WEF Local Competition (0717)||||-0.018***|||
|||||(0.005)|||
|Total natural resources rents x WEF Market Dominance<br>(0717)|||||-0.023***<br>(0.005)||
|Total natural resources rents x WGI Control of Corruption (01-<br>18)||||||-0.009*<br>(0.005)|
|Log difference of commodity Net Export Price Index (historic<br>rolling weights)|4.224**|2.367**|0.387***||||
||(1.855)|(1.041)|(0.144)||||
|Total natural resources rents (% of GDP)||||0.102***|0.108***|0.011***|
|||||(0.028)|(0.022)|(0.003)|
|Log of GDP (constant 2010 US$)|0.145***|0.144***|0.144***|0.098**|0.104**|0.100**|
||(0.053)|(0.053)|(0.053)|(0.049)|(0.050)|(0.048)|
|Constant|-3.672**|-3.663**|-3.666**|-2.333*|-2.506*|-2.401*|
||(1.525)|(1.524)|(1.523)|(1.408)|(1.430)|(1.365)|
|Billionaire Fixed Effects|YES|YES|YES|YES|YES|YES|
|Year Fixed Effects|YES|YES|YES|YES|YES|YES|
|Number of observations|20,493|20,493|20,502|18,342|18,342|18,351|
|R2|0.290|0.290|0.290|0.280|0.282|0.278|
|Adjusted R2|0.289|0.289|0.289|0.279|0.281|0.278|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level 18
# **Table 7: Commodity Price Shocks, Resource Rents and Tax Revenue Interactions**

|**Model**||**Billio**|**naire and Y**|**ear Fixed Ef**|**fects**||
|---|---|---|---|---|---|---|
|**Dependent Variable**||**Log of B**|**illionaire Ne**|**t Worth (in**|**Billions)**||
||**(1)**|**(2)**|**(3)**|**(4)**|**(5)**|**(6)**|
|Log Difference of Commodity Net Export Price Index x<br>Tax revenues (including social contributions and resource<br>taxes) (01-18)|0.016||||||
||(0.011)||||||
|Log Difference of Commodity Net Export Price Index x<br>Resource Taxes over GDP (01-18)||0.018<br>(0.052)|||||
|Log Difference of Commodity Net Export Price Index x<br>Indirect over Direct Taxes|||0.030<br>(0.020)||||
|Total natural resources rents x Tax revenues (including<br>social contributions) (01-18)||||0.0001<br>(0.000)|||
|Total natural resources rents x Resource Taxes over GDP<br>(01-18)|||||0.0005<br>(0.001)||
|Total natural resources rents x Indirect over Direct Taxes<br>(01-18)||||||0.0003*<br>(0.000)|
|Log difference of commodity Net Export Price Index<br>(historic rolling weights)|0.135|0.453***|0.164||||
||(0.206)|(0.166)|(0.174)||||
|Total natural resources rents (% of GDP)||||0.011***|0.013***|0.011***|
|||||(0.003)|(0.003)|(0.003)|
|Log of GDP (constant 2010 US$)|0.147***|0.142***|0.135**|0.099**|0.090*|0.104*|
||(0.054)|(0.053)|(0.056)|(0.048)|(0.047)|(0.060)|
|Constant|-3.743**|-3.601**|-3.392**|-2.363*|-2.129|-2.481|
||(1.536)|(1.528)|(1.614)|(1.375)|(1.357)|(1.713)|
|Billionaire Fixed Effects|YES|YES|YES|YES|YES|YES|
|Year Fixed Effects|YES|YES|YES|YES|YES|YES|
|Number of observations|20,426|19,980|19,183|18,281|17,899|17,152|
|R2|0.291|0.287|0.295|0.279|0.275|0.281|
|Adjusted R2|0.291|0.286|0.294|0.278|0.274|0.280|

note: *** p<0.01, ** p<0.05, * p<0.1, Robust Standard Errors Clustered at the Billionaire level 19
# **Table 8: Effect of Commodity Price Shocks on Tax Revenues**

|**Model**|**Country**|**and Year Fixed Effec**|**ts**|
|---|---|---|---|
|**Outcome (over GDP)**|**Tax revenues including**|**social contributions e**<br>**revenues**|**xcluding resource**|
||**(1)**|**(2)**|**(3)**|
|Log difference of commodity Net Export Price Index (historic rolling<br>weights)|-5.220***|||
||(1.450)|||
|Log Difference of Hydrocarbons Commodity Index||-0.345*||
|||(0.194)||
|Log Difference of Metals and Minerals Commodity Index||-0.500||
|||(0.321)||
|Log Difference of Agriculture, Food, and Beverages Commodity Index||-0.748*||
|||(0.442)||
|Log Difference of Crude oil Commodity Price Index|||-0.255|
||||(0.177)|
|Log Difference of Coal and Natural Gas Commodity Index|||-6.160**|
||||(2.411)|
|Log Difference of Base Metals Commodity Index|||-0.851***|
||||(0.307)|
|Log Difference of Agricultural Raw Materials Commodity Index|||-0.440|
||||(2.742)|
|Log Difference of Food Commodity Index|||-0.805*|
||||(0.474)|
|Log Difference of Beverages Commodity Index|||-0.406|
||||(1.387)|
|Log Difference of Fertilizer Commodity Index|||0.839|
||||(0.612)|
|Log Difference of Precious Metals Commodity Index|||9.863*|
||||(5.210)|
|Constant|17.214***|18.805***|18.810***|
||(0.496)|(0.541)|(0.543)|
|Country Fixed Effects|YES|YES|YES|
|Year Fixed Effects|YES|YES|YES|
|Number of observations|4,766|3,439|3,439|
|R2|0.106|0.130|0.132|
|Adjusted R2|0.099|0.120|0.121|

note: *** p<0.01, ** p<0.05, * p<0.1, robust standard errors clustered at the country level 20