Understanding the Modern Monetary System – Part 6
Part 6 is the final section in our series on understanding the modern monetary system and Monetary Realism. This section dives into some accounting identities behind the sector balances and the ways the private sector and public sector interact and drive economic growth. For a more complete discussion please review the entire paper here.
Part VI – Understanding Sectoral Balance Economics & S = I + (S-I)
It’s very important to understand the sectoral relationship within an economy and the ways in which growth is produced by the various sectors and their interdependence. Contributors to Monetary Realism find much relevance in the Sectoral Financial Balance approach as developed by Wynne Godley. It is a useful lens to help conceptualize the macro economy and to understand how the government budget relates to the current account balance and private sector saving-investment decisions. The approach is an ex-post accounting identity derived by rearranging the components of aggregate demand and it is typically presented as a three-sector model comprising the private, public and foreign sectors. It is a fundamental identity that links aggregate demand (i.e. the total amount of final goods and services purchased by agents over a given time period) with changes in sectoral net financial asset positions.
The Sectoral Financial Balance approach measures the income of the three sectors net of spending over a given time period. When any sector spends more than its income it runs a deficit and, vice versa, when a sector spends less than its income it runs surplus. It is vital to recognize that amongst the three main sectors it is the public sector (and the federal government in particular) that is most able to run large deficits over a prolonged period. This is because the budget constraint of the US federal government is not similar to that of an individual, household, business or even a state or local government.
The deficit of the entire government (federal, state, and local) is always equal (by definition) to the current account deficit plus the private sector balance (excess of private saving over investment). To be more precise: net household financial income = current account surplus + government deficit + Δbusiness non-financial assets. The private sector surplus represents the net saving of the private sector (households and businesses) from income after spending, while the public sector deficit is the government’s deficit. This is the essence of the sectoral balances approach made famous by the late great Wynne Godley. It can be visualized with the following diagram:

(Figure 3 – Sectoral Balances)
The sectoral balances can be broken down according to GDP:
GDP = C + I + G + (X – M)
Where C = consumption, I = investment, G = government spending, X = exports &M = imports
Or stated differently;
GDP = C + S + T
Where C = consumption, S = saving, T = taxes
From there we can conclude:
C + S + T = GDP = C+ I + G + (X – M)
If rearranged we can see that these sectors must net to zero:
(I – S) + (G – T) + (X – M) = 0
Where (I – S) = private sector balance, (G – T) = public sector balance & (X – M) = foreign sector balance.
The three main sectoral balances must as an accounting identity add to zero. In Figure 4 what stands out is that the US government has run budget deficits for the majority of the last 60 years (in fact well over 200 years). Equally important is that the domestic private sector balance remained in surplus until 1997 where it remained in deficit on annual basis through to the end of 2007. So why was the private sector running a deficit from 1997-2007 an ominous development? It meant that the private sector was in aggregate getting less liquid and more fragile. Disaggregation of the private sector into its subcomponent sectors (e.g. households, nonfinancial business and financial business) is needed to understand precisely how these deficits impacted on the composition of balance sheets. It remains that the negative financial balance run by the US private sector during 1997-2007 was a pointer to growing financial fragility with the crisis that began in 2007 a testament to the merits of this conceptual framework.
You can see this different version of the above chart in visual form by viewing the sectoral balances in the USA going back to 1952:

(Figure 4 – Sectoral Balances part 2)
The SFB approach underlines that when the federal government spends more than it collects in revenues the deficit spending creates net financial assets for the private sector in the form of government bonds. Private agents benefit from these net financial assets in various ways. There are investors who get a ‘safe’ interest-bearing asset for their investment portfolios. There are also the thankful recipients of the Treasury’s deficit spending who get paid for doing their business or receive a social security payment that enables them to meet their bills and survive. It’s important to note that these saving bonds are an asset of the private sector and a liability of the government. So to “pay off the national debt” would, by accounting identity, involve the elimination of an important private sector financial asset. This does not mean the government can make the private sector wealthy by providing us with government bonds, but at mentioned previously, the public sector’s constraint is different than the private sector’s constraint (solvency versus inflation) so the notion of paying off the national debt must be placed in the proper context.
The Importance of Understanding S = I + (S-I)
It’s important to take the private sector component in the sectoral balances one step further or the reader might confuse the true driver of economic growth as being the government and not the private sector. Although government can help to drive economic growth (if used properly) we should not forget that investment is the backbone of private sector equity. This simple rearrangement of the private sector component highlights this fact and helps to avoid thinking that I>S might be a negative for the economy when the reality is that a high level of Investment is generally good for the economy.
If we rearrange the above sectoral balances equation we can arrive at a very important identity:
(S – I) = (G – T) + (X – M)
S = I + (G – T) + (X – M)
Which rearranges to:
S = I + (S – I)
We can also think of this from the National Income Accounting equation:
C + I + G + (X – M) = C + S + T
Which rearranges to:
(S-I) + (T-G) + (M-X) = 0
Which rearranges to:
I = S + (T-G) + (M-X)
This helps to show the reader that wealth creation is not just achieved through government deficit spending, but largely occurs independent of government. On this point it’s important to understand the difference between real wealth and financial wealth. A good way to think about all of this is to understand that the private sector can create real wealth entirely independent of the government. A farmer does not need the government to turn 2 cows into 10. The farmer has achieved real wealth creation regardless of the government’s spending position. What the government must generally do over time is help to facilitate the wealth accumulation process by providing the net financial assets to help the private sector monetize this real wealth and sustain its demand for saving. It’s important not to put the cart before the horse here. It’s best to think of government as being a facilitator of wealth creation and not the driver. Hence, our focus on S=I+(S-I) with the emphasis on the idea that “the backbone of private sector equity is I, not Net Financial Assets.” The idea is not novel, but simply clarifies the understanding of the private sector component.
Turning quickly to the data, the US general government deficit averaged around one-sixth of gross private domestic investment during the period 1960-2007, and fourth-fifths during 2008-2010. It should not be controversial at all that the main driver of private saving is usually private investment but that during economic downturns the role of general government deficit-spending becomes more important.
MR understands that consumption and production are two sides of the same coin, but it is through production that we grow the coin. We highlight this point by expanding on the sectoral balances equation and showing that S = I + (S-I) in order to emphasize that I>S does not mean the private sector financial position is necessarily deteriorating or experiencing a “net loss”. So while the sectoral balances equation is useful in understanding the dynamic of the system it should not be used to imply that the private sector’s financial position is necessarily deteriorating because I>S . When one takes this perspective you bring a more balanced understanding of the way our monetary system actually works.
Private sector saving can be decomposed into the amount of saving created by investment “I” and the amount of net financial assets transferred from other sectors (S – I). That is the focus of the equation S = I + (S – I) as it highlights the fact that the private sector is the primary driver of economic prosperity while government is a powerful facilitator.
It’s important not to overstate the idea of “net financial assets”. “Net financial assets” (NFA) as a source of savings and vehicle for private agents to accumulate wealth is more at the margins than the center. There is no debate that T-bonds play a crucial role enabling deficit-spending and providing ‘safe’ collateral for private agents; however, the importance of financial claims issued by the public sector and held by private agents is drastically elevated when focusing on net positions instead of gross positions. Consider that at year-end 2011 the volume of US Treasury debt outstanding was $10.5tr while the value of financial assets summed across the private sectors was $130.4tr (yes there is some double-counting) and the value of household sector total assets was $72.3tr of which $49.1tr was financial assets. At year-end 2010 the market value of US private sector assets held abroad was $19.8tr. When taking into account that just under half of US T-bonds are held by foreign agents it is clear that the role of the Treasury supplied NFAs as a source of savings and vehicle for private agents to accumulate wealth is relatively modest.
When one connects the dots between production and the MR Law you can begin to understand why private sector production matters so enormously to the living standards of the society. In this regard, I is the core of improved living standards, because it is through I that we create things that make us more productive and therefore give us more time. But we must maintain a balance here and never forget that government can be an important facilitator of the wealth accumulation process who wields powerful tools that can aid us in driving demand, stabilizing economic growth and helping to improve overall living standards.
Conclusion
In sum, most of what we have been taught in school is based on a now defunct monetary system (the gold standard). Monetary Realism seeks to describe the operational realities of a modern fiat currency system. While its description of the modern monetary system is accurate, it is by no means a holy grail. And those who apply policy prescriptions are merely utilizing the realities of the system to apply what they believe are sound uses of the system. It does not mean the government can just credit accounts and create real wealth.
One of the key understandings here is that government can be used as a tool to help the private sector to achieve prosperity. I think it’s important to understand that government is not always bad or that government spending is always evil. In fact, government serves a vital purpose within our society. How involved that government is in the day to day lives of its citizens is to be decided by the citizens themselves.
I believe Monetary Realism provides a more accurate portrayal of the monetary system in which we reside in the USA and in many other autonomous countries throughout the world. It is my hope that a greater understanding of our monetary system will result in a less dogmatic, more pragmatic and more rational perspective of our economy so as to help us all in achieving the prosperity we desire.












7 Comments
Both Mish and Keen are right, but neither have a fully formed solution.
Keen would keep private banks the same as they are, but tighten up “private credit” formation with new regulations. For example, you would have to put a large deposit down to get a mortgage. By spending directly with quantitative easing for the public, means that everybody gets a QE check. That check goes on to pay down the asset column at the private bank. This changes the structure of personal debt, meaning the bank makes less future profit. Less debt service, means wallet money should go toward productivity consumption rather than debt service. (How do you make sure new subsequent loans aren’t more asset inflation and unproductive debts?) Those folks not in debt get a check also, to spend on the productive side of the economy.
If I were Keen, I’d suggest the extra checks (those people not in debt) have to go toward some sort of public commons, which has extra payoff in improved productivity. For example, new ports, bridges, rail, or whatever we deem is important for the future of the country. The spending could be in the form of a targeted bond, like the old German MefoBills. They used MefoBills as a labor token that bought infrastructure e.g. the autobahn; it was spent as money and paid interest when it drained back to the treasury.
Mish is right in that it is private credit formation at the root of the problem, and it needs to be abolished outright. Fractional reserve principles, that is credit formation, has an illogical fallacy at its core. Consider that 90% of the money supply is always draining toward private banks, and new supply must always come on line so we have something to trade with. This makes a treadmill of debt and a permanent oligarchy; a bane of civilization. Making new money to get between credit and debt annihilation is not a trusted position, and banks should not be involved in it.
As many know, I’ve proposed fully reserved private banks. This means that money bounces back and forth between creditor and debtors, without a lot of new money having to be created to fill the supply. Money from the past, already in the supply serves as our token arbiter in trade, and hence it doesn’t drag inefficient debts with it. Money in that case serves as a token that allows us to trade out output, and it doesn’t take a lot of wealth for its right to exist.
You would need a component of state credit (future money based on risk); where the drain points back to the treasury. When you pay back the loan it drains toward the creator of money, the treasury, where it belongs. Since the drain points correctly, it can be law based and go through easy debt jubilees (or loan restructuring) should they be needed (unlikely). As well, interest rates could be controlled as the the fully reserved component at private banks follows the state credit component.
The money system has to change, there is no fixing something that has an illogical fallacy at its core.
MMR analysis is something like an electrical engineer understanding their circuits. Understanding the electron that flows in the circuit is more physics and science. I’m hoping and having faith that the MMR people will evolve to look at money itself and not just the system. That said, any system predicates its output, and money itself cannot be divorced from its system context. So MMR people, you have to become both engineers and scientists. If we only want to know the money system so you can profit from it, shifting wealth from the producers, then… it that really what we stand for?
Money is an accounting identity that flows in the money supply pipes, and it changes form as it flows, depending on its location and demands. For example, money can be a unit of exchange as it has velocity, or it can stop having velocity and then it demands to be an asset. As an asset it then demands interest inputs. There is no analog in the real world, where an electron demands more electrons as it stop flowing. The usury error is a function of the human mind, where we expect the loaning of assets to bring in more assets. This growth applies to the natural world, where said growth is a function of energy inputs from the sun; but it is unnatural to man-made accounting identities, unless the money system designs for it.
Humans create credit and debts in their minds, as part of their mathematical nature. When I loan you a chicken, a rubicon is crossed in my mind and yours. I become a creditor and you a debtor. If you pass the chicken back to me immediately, the credits and debts are wiped out in the here and now. No money exchanged hands, but credits and debts were created. Marking of credits and debts evolved to making marks on paper, such as tallies. Tallies are a low form of money that has high information (info on the Chicken and when it is to be paid, and if there is any egg or chick interest); but tallies do not let credits and debts extinguish in the here and now.
Money allows credits and debts to extinguish, or annihilate into nothingness. But, unlike the tally, money codes for low information and we assume much when we look at it. We assume the money system predicates behavior properly
If I loan you four chickens and you immediately give me back four chickens, and credits and debts go to zero in our minds. Money allows credits and debts to extinguish in the now, when it acts as go between arbiter. However, money itself can also act as an asset because it supposedly has value. The value is the ability of the law and force to mediate the money contract between credit and debt.
If you don’t pay me back the chicken and some egg interest, then the law steps in. If you still don’t pay, then maybe force is involved. Money then exists simultaneously with law and force in the space BETWEEN credit and debt. I can loan you a chicken asset, or I can loan you money as an asset. The system must code for this. All of history and our future are predicated on getting this right. Marx got it wrong, and today’s economist get it wrong.
Bank money, or credit money, makes a market in money. It then, like a thief, steps into the space between credit and debt and attaches itself to the market. This is a fundamental flaw in logic. Banks should only shuffle money between accounts as Joe pays Maria who pays John.
By making a market in money and attaching to markets, credit then controls the marketplace. The feedback loops also code for asset inflation, as credit can drive the same assets attached to the ledger, driving more credit. Markets are not God; they are creatures of law and money information (volume and velocity) feedbacks. Banks can manipulate volume and velocity, and the usury drains toward them.
For capitalism to survive, the money system must code properly and allow debts and credits to extinguish with maximum efficiency. The time hypothesis times zero efficiency multiplies out to zero. The dark ages are an example of low efficiency outputs as the money system coded for oligarchy.
I have faith that MMR folks will evolve their models to include the behavior of money itself, to become more scientists rather than engineers. Keep up the good work, but please look more closely at private credit.
“It remains that the negative financial balance run by the US private sector during 1997-2007 was a pointer to growing financial fragility with the crisis that began in 2007 a testament to the merits of this conceptual framework.”
“This simple rearrangement of the private sector component highlights this fact and helps to avoid thinking that I>S might be a negative for the economy when the reality is that a high level of Investment is generally good for the economy.”
These two statements are contradictory, since ‘the negative financial balance run by the US private sector’ is equivalent to ‘I>S’ (S-IS’ oversimplifies and overstates this.
More appropriate would be a ratio comparing the magnitude of I relative to S (and perhaps ratios to C and GDP as well). Thus, your specific example reflects the ratio I/(S-I), >>1 for ’60-’07, vs >= 1 for ’08-10.
(While supporting the relative importance of I during most of the postwar period, this example also supports the Keynsian emphasis on the role of government deficits during hard times.)
While the discussion towards the end gives some concrete sense of what S, I and S-I are referring to, I think more of this near the beginning of this section are needed to make it generally accessible.
generally. It would be foolish for me to say that all investment is good all the time. Obviously, the investment boom during the housing bubble was debt fueled and helped create a fragile economic environment. I should probably qualify that statement more clearly….
Correction: middle paragraph should read:
These two statements are contradictory, since ‘the negative financial balance run by the US private sector’ is equivalent to ‘I>S’ (S-IS’ oversimplifies and overstates this.
Sorry, it still didn’t come out right. Should read:
These two statements are contradictory, since ‘the negative financial balance run by the US private sector’ is equivalent to ‘I>S’ (S-IS’ oversimplifies and overstates this.
OK, I get it, The carets are being treated as HTML, Lets try just the last sentence of the paragraph:
I understand that the point is to emphasize the role of I, but reference to the highly atypical case of ‘I>S’ oversimplifies and overstates this.