Payday loan shop, Soho, London

9 The credit market: Borrowers, lenders, and the rate of interest

9.1 Introduction

  • People with wealth are able to borrow substantial amounts, and they often lend money to less-wealthy people.
  • People can rearrange the timing of their spending by borrowing, lending, investing, and saving.
  • While mutual gains for both borrowers and lenders motivate credit market transactions, there is a conflict of interest between them over the rate of interest, the prudent use of loaned funds, and the repayment of loans.
  • Borrowing and lending is a principal-agent relationship in which there is no enforceable contract that can guarantee for the lender (the principal) that the loan will be repaid by the borrower (the agent).
  • To solve this problem, lenders often require borrowers to contribute some of their own funds to a project as collateral or equity.
  • People with limited wealth are unable to contribute collateral or equity, and as a result are often unable to secure loans or can only do so at higher interest rates.

The market town of Chambar in southeastern Pakistan serves as the financial centre for 2,400 farmers in surrounding villages. At the beginning of the kharif planting season in April, when the farmers sow cotton and other cash crops, they buy fertilizer and other inputs. Months have passed since they sold the last harvest, and so the only way they can buy inputs is to borrow money, promising to repay at the next harvest. Others borrow to pay for medicines or doctors.

But few farmers have ever walked through the shiny glass and steel doors of the JS Bank on Hyderabad Road. Instead, they visit one of approximately 60 moneylenders.

If they are seeking a first-time loan, they will be questioned intensively by the moneylender, asked for references from other farmers known to the lender, and in most cases given a small trial loan as a test of creditworthiness. The lender will probably visit to investigate the condition of a farmer’s land, animals, and equipment.1

The lenders are right to be wary. If the farmer’s crop fails due to drought or lack of attention, the lender will make a loss. Unlike many financial institutions, lenders do not usually require that the farmer set aside some property or belongings—for example, some gold jewelry—that would become the lender’s property if the farmer does not repay the loan.

If the would-be first-time borrower looks reliable or trustworthy enough, the farmer is offered a loan. In Chambar, this is at an average interest rate of 78% per annum. If the borrower pays the loan back in four months (the growing period of the crop prior to harvest), 100 rupees borrowed before planting is paid back as 126 rupees. But, knowing that more than half the loan applications are refused, the borrower would feel fortunate.

And indeed, the borrower in Chambar would be, at least compared to some people 12,000 km away in New York, who take out short-term loans to be repaid when their next paycheck comes in. These payday loans bear interest rates ranging from 350% to 650% per annum, much higher than the legal maximum interest rate in New York (25%). In 2014, the ‘payday syndicate’ offering these loans was charged with criminal usury in the first degree.2

Given the interest rates charged, is the business of lending in Chambar or of payday loans in New York likely to be exceptionally profitable? The evidence from Chambar suggests it is not. Some of the funds lent to farmers are borrowed from commercial banks, like the JS Bank, at interest rates averaging 32% per annum, representing a cost to the moneylenders. And the costs of the extensive screening of borrowers and collection of the debts further reduces the profits made by the moneylenders.

Partly as a result of the careful choices made by the moneylenders in Chambar, default is rare—fewer than one in 30 borrowers fail to repay. By contrast, default rates on loans made by commercial banks are much higher—one in three. The moneylenders’ success in avoiding default is based on their accurate assessment of the likely trustworthiness of their clients.

Not everyone passes the trustworthiness tests set by the moneylenders and the payday lenders—some would-be borrowers find it impossible to get a loan. And, in Chambar and New York, some of those who do, pay much higher interest rates than others.

Long before there were the employers, employees, and the unemployed that we studied in the previous unit, there were lenders and borrowers. Some of the first written records of any kind were records of debts. Differences in income between those who borrow—like the farmers in Chambar and those seeking payday loans in New York—and those who lend—like the money lenders in Chambar and the payday lenders in New York—remain an important source of economic inequality today.

In this unit, we study borrowers and lenders and the workings of the market for credit. We examine the nature of the benefits that arise from lending and borrowing; we also show how the nature of credit markets can limit those benefits. Like the labour market, the credit market is essential to the functioning of a capitalist economy, and also like the labour market the credit market differs in important ways from the markets for bread, language courses, and the other goods and services studied in Unit 7.

9.2 Income, consumption, and wealth

In everyday language, terms like ‘money’, ‘wealth’, and ‘investment’ are often used loosely. We hear people say: ‘I want a job that pays good money,’ or: ‘I want to invest some money for when I retire,’ or: ‘I need to borrow some money to see me through to the end of the month.’

To understand the credit market, we need to clarify how these terms are used in economics.

It turns out that, for economists, one of the trickiest things to define precisely is money. Economists like to define money in terms of what it does. They point to a number of functions that money fulfils. Some of these functions are also fulfilled by other things, but only money fulfils all these functions. We shall delve deeper into these functions in Unit 10.

But at this stage, we only need to think about one function of money—money is a ‘store of value’. In simple terms, this means that anyone who has money can turn it into goods and services. When people say they want more money, what they really want is more of the goods and services that money will buy.


consumption (C)
Expenditure on both short-lived goods and services and long-lived goods, which are called consumer durables. See also: consumer durables.
  • ‘I want a job that pays good money,’ means: ‘I want a job that enables me to have more stuff.’
  • ‘I want to invest some money for when I retire,’ means: ‘I want to postpone some of my consumption of goods and services until I retire.’
  • ‘I need to borrow some money to see me through to the end of the month,’ means: ‘I want to bring forward some spending so that I can maintain my desired level of consumption until the end of the month.’ (It is, crucially, a bringing forward, since borrowing means that higher consumption this month must imply lower consumption at a later date).

Why are our paraphrases more precise than the original sentences? In each case, they focus on the person’s motivation. One way to show this is to note that money itself does not play a unique role in the original sentences. Thus:

  • ‘I want a job with good fringe benefits,’ still means: ‘I want a job that enables me to have more stuff.’
  • ‘I want to invest in the stock market for when I retire,’ still means: ‘I want to postpone some of my consumption of goods and services until I retire.’
  • ‘I need to increase my overdraft to see me through to the end of the month,’ still means: ‘I want to bring forward some spending so that I can maintain my desired level of consumption until the end of the month.’
investment (I)
Expenditure on newly produced capital goods (machinery and equipment) and buildings, including new housing.
Stock of things owned or value of that stock. It includes the market value of a home, car, any land, buildings, machinery, or other capital goods that a person may own, and any financial assets, such as bank deposits, shares, bonds, or loans made to others. Debts to others are subtracted from wealth—for example, the mortgage owed to the bank.

In this unit, we shall postpone any further discussion of money. We first focus on consumption and investment directly in terms of goods and services, and on wealth as potential spending power. We then analyse the role of borrowing and lending in allowing us to shift spending across time. We return to the topic of what money is and does in Unit 10.


One way to think about the amount of wealth that you have as a household is that it is the largest amount that you could spend without borrowing, after having paid off your debts and collected any debts owed to you—for example, if you sold your house, car, and everything you owned.

The amount of labour earnings, dividends, interest, rent, and other payments (including transfers from the government) received by an economic actor, net of taxes paid, measured over a period of time, such as a year. The maximum amount that you could consume and leave your wealth unchanged. Also known as: disposable income. See also: gross income.
human capital
The stock of knowledge, skills, behavioural attributes, and personal characteristics that determine the labour productivity or labour earnings of an individual. It is part of an individual’s endowments. Investment in this through education, training, and socialization can increase the stock, and such investment is one of the sources of economic growth. See also: endowment, labour productivity.
Wages, salaries, and other income from labour.
flow variable
A quantity measured per unit of time, such as annual income or hourly wage. See also: stock variable.
stock variable
A quantity measured at a point in time. Its units do not depend on time. See also: flow variable.
disposable income
Income available after paying taxes and receiving transfers from the government.
The loss in value of a form of wealth that occurs either through use (wear and tear) or the passage of time (obsolescence).

The term wealth is also sometimes used in a broader sense to include immaterial or intangible aspects, such as your health, skills, and ability to earn an income (your human capital). But we will use the narrower definition of material wealth in this unit since we focus on forms of wealth that can potentially be turned into spending on goods and services.


Income is the amount of money you receive over some period of time, whether from market earnings, assets that you own, or as transfers from the government.

Since it is measured over a period of time (such as weekly or yearly), it is a flow variable illustrated below in Figure 9.1. Wealth is a stock variable, meaning that it has no time dimension. At any moment of time it is just there. In this unit, we only consider after-tax income, also known as disposable income.

To highlight the difference between wealth and income, think of filling a bathtub, as in Figure 9.1. Wealth is the amount (stock) of water in the tub, while income is the flow of water into the tub. The inflow is measured by litres (or gallons) per minute; the stock of water is measured by litres (or gallons) at a particular moment in time.

Figure 9.1 Wealth, income, depreciation, and consumption: The bathtub analogy.

As we have seen, some wealth takes physical forms, such as a house, or car, or office, or factory. The value of physical wealth tends to decline, either due to use or simply the passage of time. This reduction in the value of a stock of wealth over time is called depreciation. Using the bathtub analogy, depreciation is the amount of evaporation of the water. In economics, an example of depreciation is the fall in the value of a car with mileage and with age. Like income, depreciation is a flow (for example, you could measure it in dollars per year for a car or computer), but a negative one.

When we take account of depreciation, we must distinguish between net income and gross income. Gross income is the flow of disposable income into the bathtub. It either adds to wealth, is used for consumption spending or is lost as depreciation. Before the income enters the bathtub, taxes are subtracted and transfers are added, such as pension payments from the government. Net interest receipts are part of the flow into the bathtub, and so are net receipts of transfers from others (such as gifts).

income net of depreciation
Disposable income minus depreciation. See also: disposable income, gross income, depreciation.
When consumption expenditure is less than net income, saving takes place and wealth rises. See also: wealth.

Income net of depreciation is the maximum amount that you could consume and leave your wealth unchanged.

Consumption, saving, and investment

Water also flows out of the tub. The flow through the drain is called consumption, and it reduces wealth just as net income increases it.

Measured consumption includes spending on goods that provide services over long periods of time, like screens, bicycles and cars. Where the services are provided over a very long period as for new housing, the spending is classified as investment.

An individual (or household) saves when consumption is less than net income, so wealth increases. Wealth is the accumulation of past and current saving. Saving can take a number of forms, for example, in bank deposits, or in financial assets, such as shares (also known as stocks) in a company or a government bond. These are often held indirectly by investing in a pension fund. In everyday language these purchases are sometimes referred to as ‘investment’, but in economics investment means spending on capital goods that provide services over long periods of time, such as equipment or buildings.

The distinction between investment and purchasing shares or bonds (sometimes called financial investment) is illustrated by a sole proprietor business. At the end of the year, the owner decides what to do with her net income. Out of the net income, she decides on her consumption expendit­ure for the year ahead and saves the remainder, so her wealth rises.

With her savings, she could buy financial assets that provide funds to businesses or the government, such as shares or bonds. Contributions to a personal pension fund are an example of the use of savings to buy financial assets. Or, instead, she could spend on new assets such as computers to expand her business, which would be investment expenditure.

To summarize: in this example, the wealth of the owner of the small business has increased. The form that the increase in wealth takes is a combination of money (bank deposits), financial assets (bonds, shares, and pension fund assets), and physical assets (computer equipment for her business).

Lending and borrowing

Households borrow from banks, finance companies, payday lenders, or from other individuals to spend on consumer durables and nondurables and for the purchase of housing. Businesses and governments also borrow; when a household buys bonds with their savings, they are making a loan to the government (a government bond) or to a business (a corporate bond).

Question 9.1 Choose the correct answer(s)

Which of the following statements are correct?

  • Your material wealth is the largest amount that you can consume without borrowing; it includes the value of your house, car, financial savings, and human capital.
  • Income net of depreciation is the maximum amount that you can consume and leave your wealth unchanged.
  • In economics, investment means saving in financial assets, such as shares and bonds.
  • Depreciation is the loss in your financial savings due to unfavourable movements in the market.
  • Human capital, such as your health, skills, and ability to earn an income, is immaterial wealth.
  • Income net of depreciation is the flow that corresponds to your stock of wealth, so if you consume it all, your wealth is unchanged.
  • Although in everyday language the purchase of financial assets is sometimes referred to as investment, in economics, investment means expenditure on capital goods, such as machinery, equipment, and housing.
  • Depreciation is the loss in value through wear and tear or the passage of time.

Question 9.2 Choose the correct answer(s)

Mr Bond has wealth of £500,000. He has a market income of £40,000 per year, on which he is taxed 30%. Mr Bond’s wealth includes some equipment, which depreciates by £5,000 every year. Based on this information, which of the following statements are correct?

  • Mr Bond’s disposable income is £40,000.
  • Mr Bond’s net income is £28,000.
  • The maximum amount of consumption expenditure possible for Mr Bond is £23,000.
  • If Mr Bond decides to spend 60% of his net income on consumption and the rest on investment, then his investment is £9,200.
  • Mr Bond’s disposable income is his market income less tax, which is £40,000 × 0.7 = £28,000.
  • Mr Bond’s net income is his disposable income minus depreciation, which is £28,000 – £5,000 = £23,000.
  • £23,000 is Mr Bond’s net income. Consuming this amount does not alter his wealth. However, Mr Bond can also consume all of his wealth, so his maximum possible consumption expenditure is £500,000 + £23,000 = £523,000.
  • Sixty per cent of his net income is £13,800, leaving £9,200 to spend on investment.
indifference curve
A curve of the points which indicate the combina­tions of goods that provide a given level of utility to the individual.
Pro-and-con evaluations of the possible outcomes of the actions we may take that form the basis by which we decide on a course of action.
opportunity cost
The opportunity cost of some action A is the foregone benefit that you would have enjoyed if instead you had taken some other action B. This is called an opportunity cost because by choosing A you give up the opportunity of choosing B. It is called a cost because the choice of A costs you the benefit you would have experienced had you chosen B.

9.3 Borrowing: Bringing consumption forward in time

Borrowing and lending are about shifting consumption and production over time. The moneylender offers funds to the farmer to purchase fertilizer now, to pay back after the crop matures, as long as the harvest is good. The payday borrower will be paid at the end of the month but needs to buy food now. The borrower brings some future buying power to the present.

To understand borrowing and lending, we will use feasible sets and indifference curves. In Unit 4 and Unit 5, you studied how Alexei and Angela make choices between conflicting objectives, such as free time and grades or grain. They made choices from the feasible set, based on preferences described by indifference curves that represented how much they valued one objective relative to the other.

Here, you will see that the same feasible set and indifference curve analysis apply to choosing between having something now and having something later. In earlier units we saw that giving up free time is a way of getting more goods, or grades, or grain. We shall see that giving up some goods to be enjoyed now will sometimes allow us to have more goods later. The opportunity cost of having more goods now is having fewer goods later.

Borrowing and lending allow us to rearrange our capacity to buy goods and services across time. Borrowing allows us to buy more now but constrains us to buy less later.

To see how this works, think about Julia. She can count on her family (now and in the future) to provide the bare necessities. But she would like to consume more now. She may be a payday borrower in New York City or a farmer in Chambar at planting time, or perhaps she has just graduated and needs to finance a period before her first job begins.

Julia knows that, in the next period (‘later’), she will have $100 when she is paid or when the crop is sold. Julia’s situation is shown in Figure 9.2. Each point in the figure shows a given combination of Julia’s consumption beyond the bare necessities provided by her family—both now (measured on the horizontal axis) and later (measured on the vertical axis).

We will use a figure like this throughout the unit, and often refer to the ‘slope’ of lines and curves that we draw. You may remember from studying geometry that, when a line slopes downwards from left to right, the slope is negative. This is logical—to get more income now (a positive change), Julia accepts less income later (a negative change).

When economists talk about the ‘slope’ of the trade-off between now and later, they usually simplify things in the description by using the positive value of this number. This is called taking the absolute value of the slope. When we refer to the ‘slope’ of a line or curve in this unit, we will refer to the absolute value, and so the slope is always a positive number. You will find this is easier when you are describing the trade-off that borrowers make.

Julia is not free to simply pick any combination of consumption now and later. She has to buy what she consumes over and above what her family provides.

Figure 9.2 Borrowing, the interest rate, and the feasible set.

Julia has nothing

Julia has no money now but she knows that, in the next period, she will have $100. Given this state of affairs, her consumption now is $0 and $100 later. This point is labelled as her endowment. It is what she has now or expects to get before any other interaction, such as borrowing.

Bringing future income to the present

Assuming an interest rate of 10%, Julia could, for example, borrow $91 now and promise to pay the lender the $100 that she will have later, assuming an interest rate of 10%.

Borrowing less

At the same interest rate (10%), she could also borrow $70 to spend now, and repay $77 at the end of the year. In that case, she would have $23 to spend next year.

Borrowing even less

At the same interest rate (10%), she could also borrow $30 to spend now, and repay $33 at the end of the year. In that case she would have $67 to spend next year.

Julia’s feasible set

By repeating these hypothetical borrowing and repayment combinations, the boundary of Julia’s feasible set—called her feasible frontier—is formed. This is shown for the assumed interest rate of 10%.

Julia’s feasible frontier

If Julia can borrow at 10%, she can move from her endowment by borrowing now and choose any combination on her feasible frontier.

A higher interest rate

If, instead of 10%, the interest rate is 78%, Julia can only borrow a maximum of $56 now.

The feasible set

The feasible set with the interest rate of 78% is the dark shaded area, while the feasible set with an interest rate of 10% is the dark shaded area plus the light shaded area.

A closer look at borrowing

In Figure 9.2, Julia is at the point labelled ‘Julia’s endowment’. To consume at least something now, Julia considers taking out a loan, as shown.

interest rate
The price of bringing some spending power forward in time. See also: nominal interest rate, real interest rate.

If the interest rate were 10%, Julia could, for example, borrow a bit less than $91 now and promise to pay the lender the whole $100 that she will have later. Her total repayment of $100 would include the principal (how much she borrowed, namely $91) plus the interest charge ($9) at the rate r, or:

And if ‘later’ means in one year from now, then the annual interest rate, r, is:

You can think of the interest rate as the price of bringing some spending power forward in time.

At the same interest rate (10%), Julia could also borrow $70 to spend now, and repay $77 at the end of the year, that is:

In this case, she would have $23 to spend next year. Another possible combination is to borrow and spend just $30 now, which would leave Julia with $67 to spend next year, after repaying her loan.

feasible frontier
The curve made of points that defines the maximum feasible quantity of one good for a given quantity of the other. See also: feasible set.

All of her possible combinations of consumption now and consumption later, for example ($91, $0), ($70, $23) ($30, $67), are the points that make up the feasible frontier shown in Figure 9.2. This is the boundary of the feasible set when the interest rate is 10%.

The fact that Julia can borrow means that she does not have to consume only in the later period. She can borrow now and choose any combination on her feasible frontier. But the more she consumes now, the less she can consume later. With an interest rate of r = 10%, the opportunity cost of spending one dollar now is that Julia will have to spend 1.10 = 1 + r dollars less later.

marginal rate of transformation (MRT)
A measure of the trade-offs a person faces in what is feasible. Given the constraints (feasible frontier) a person faces, the MRT is the quantity of some good that must be sacrificed to acquire one additional unit of another good. At any point, it is the slope of the feasible frontier. See also: feasible frontier, marginal rate of substitution.

One plus the interest rate (1 + r) is the marginal rate of transformation of goods from the future to the present, because to have one unit of the good now, you have to give up 1 + r goods in the future. This is the same concept as the marginal rate of transformation of goods, grain, or grades into free time that you encountered in Units 4 and 5.

A higher interest rate raises the price of bringing buying power forward

Suppose that, instead of 10%, the interest rate is 78%, the average rate paid by the farmers in Chambar. At this interest rate, Julia can now only borrow a maximum of $56, because the interest on a loan of $56 is $44, using up all $100 of her future income. Her feasible frontier therefore pivots inward and the feasible set becomes smaller. Because the price of bringing buying power forward in time has increased, the capacity to consume in the present has fallen, just as your capacity to consume grain would fall if the price of grain went up (unless you are a producer of grain).

conflict of interest
The situation which arises if in order for one party to gain more from the interaction, another party must do less well.

Of course, the lender will benefit from a higher interest rate (as long as the loan is repaid) so there is a conflict of interest between the borrower and the lender.

Exercise 9.1 Julia’s feasible frontier

We construct Julia’s feasible frontier by finding all the combinations of consumption now and next period, given her endowment and the interest rate.

  1. Complete the table below, using the information given. Round your answers to the nearest dollar.
  2. Using your completed table, draw a diagram similar to Figure 9.2, showing the feasible frontier, consumption amounts and the amount of repayment.

Point on the feasible frontier Consumption now Consumption later Repayment
Calculation = amount borrowed = income later − repayment = income later − (1 + r) × amount borrowed = income later − consumption later
Endowment point
(0, 100) 0 100 0
Interest rate = 10%
(91, 0) 91 100 − (1.1)91 = 0 100
(70, 23)
(30, 67) 30 33
Interest rate = 78%
(56, 0) 56 100 − (1.78)56 = 0 100

9.4 Reasons to borrow: Smoothing and impatience

consumption smoothing
Actions taken by an individual, family, or other group in order to sustain their customary level of consumption. Actions include borrowing or reducing savings to offset negative shocks, such as unemployment or illness; and increasing saving or reducing debt in response to positive shocks, such as promotion or inheritance.

Given the opportunities for bringing forward consumption shown by the feasible set, what will Julia choose to do? How much consumption she will bring forward depends on how impatient she is. She could be impatient for two reasons:

  • She prefers to smooth out her consumption instead of consuming everything later and nothing now.
  • She may be an impatient type of person.


The first reason is that she would like to smooth her consumption because she enjoys an additional unit of something more when she has not already consumed a lot of it. Think about food—the first few bites of a dish are likely to be much more pleasurable than bites from your third serving. This is a fundamental psychological reality, sometimes termed the law of satiation of wants.

diminishing marginal returns to consumption
The value to the individual of an additional unit of consumption declines, the more consumption the individual has. Also known as: diminishing marginal utility.

More generally, the value to the individual of an additional unit of consumption in a given period declines the more that is consumed. This is called diminishing marginal returns to consumption. You have already encountered something similar in Unit 4, when Alexei experienced diminishing marginal returns to free time. Holding his grade constant, the more free time he had, the less each additional unit was worth to him, relative to how important the grade would be. We can apply this to consumption in general. Diminishing marginal returns imply that we prefer to smooth our consumption. We would optimally choose to consume similar amounts now and later, as Figure 9.3 shows.

Figure 9.3 Consumption smoothing: Diminishing marginal returns to consumption.

Julia’s choices

The dashed line shows the combinations of consumption now and consumption later from which Julia can choose.

Diminishing marginal returns to consumption

Julia’s indifference curve is bowed toward the origin as a consequence of diminishing marginal returns to consumption in each period. The more goods she has in the present, the less she values an additional one now relative to more in the future. The slope of the indifference curve is the marginal rate of substitution (MRS) between consumption now and consumption later.

What choices would Julia make?

The MRS at C is high (the slope of her indifference curve is steep)—Julia has little consumption now and a lot later, so diminishing marginal returns mean that she would like to move some consumption to the present. The MRS at E is low. She has a lot of consumption now and less later, so diminishing marginal returns mean that she would like to move some consumption to the future. So she will choose a point between C and E.

MRS falls

We can see that the MRS is falling as we move along the indifference curve from C to E. The slope is steeper at C than at E.

Julia’s optimal choice

Given the choice shown by the line CE, Julia will choose point F. It is on the highest attainable indifference curve. She prefers to smooth consumption between now and later.

Pure impatience, or how impatient you are as a person

If Julia knows she can have two meals tomorrow but she has none today, then diminishing marginal returns to consumption could explain why she might prefer to have one meal today and one tomorrow. Note that Julia would opt for the meal now, not because she is an impatient person, but because she does not expect to be hungry in the future. She prefers to smooth her consumption of food.

pure impatience
In a situation in which a person’s endowment is the same amount of consumption this period and later, she would have this characteristic if she values an additional unit of consumption now over an additional unit later. It arises when a person is impatient to consume more now because she places less value on consumption in the future for reasons of myopia, weakness of will, or for other reasons. See also: weakness of will.

But there is a different reason for preferring the good now, called pure impatience. To see whether someone is impatient as a person, we ask whether, if she initially had the same amount of the good in both periods, she would value having more of the good now more highly than more of the good later? Two reasons for pure impatience are:

  • Myopia (short-sightedness): People experience the present satisfaction of hunger or some other desire more strongly than they imagine the same satisfaction at a future date.
  • Prudence: People know that they may not be around in the future, and so choosing present consumption may be a good idea.

We saw that Julia, who will earn $100 in the future, wants to borrow. The situation that she is in gives her a strong desire to smooth by borrowing. Think about what Julia’s indifference curve, passing through her endowment point, might look like. As shown in Figure 9.4, she has a strong preference for increasing consumption now.

reservation indifference curve
A curve that indicates allocations (combinations) that are as highly valued as one’s reservation option. See also: reservation option.

This is called Julia’s reservation indifference curve, because it is made of all the points at which Julia would be just as well off as at her reservation position, which is her endowment with no borrowing or lending. Julia’s endowment and reservation indifference curves are similar to those of Angela, the farmer, in Unit 5. At point A, with no expenditure at all on consumption now, we assume Julia has some way of maintaining herself.

Figure 9.4 Julia’s indifference curves.

Figure 9.4 shows Julia’s indifference curves:

  • Her reservation indifference curve: The curve closest to the origin.
  • Her reservation indifference curve if she had the $100 now: The next-highest curve assumes that she has already earned $100.
  • A higher indifference curve.
Any preference to move consumption from the future to the present. This preference may be derived either from pure impatience or diminishing marginal returns to consumption.
discount rate
A measure of a person’s impatience: how much that person values an additional unit of consumption now relative to an additional unit of consumption later. It is the absolute value of the slope of a person’s indifference curve for consumption now and consumption later, minus one. Also known as: subjective discount rate.
A numerical indicator of the value that one places on an outcome, such that higher-valued outcomes will be chosen over lower-valued ones when both are feasible.

For any particular point in the figure, the individual’s impatience can be seen from the steepness of the indifference curve. At her endowment point—$100 later, nothing now—shown by point A, her indifference curve is very steep. Because she has nothing now, she is very impatient. It means she would be willing to give up a substantial amount of consumption later to gain a little bit of consumption now. This could be illustrated by a move from point A to A’.

We define a person’s discount rate, (economists use the Greek letter rho, as the slope (remember, we take the absolute—positive—value) of the indifference curve minus one. It is a measure of impatience, namely how much Julia values an extra unit of consumption now, relative to an extra unit of consumption later.

Her discount rate , which measures her impatience, depends both on her desire to smooth consumption and on her degree of pure impatience. A high discount rate means a high degree of impatience.

Notice in Figure 9.4 that if Julia hypothetically had the $100 now (point B), she would be much less impatient; at B, her indifference curve is very flat, which means that she would like to have more consumption in the future and less now and would be willing to give up a dollar now, even if she got less than a dollar in return later.

Not only would Julia be less impatient at point B (with $100 now) than at point A (in her initial situation of having $100 later), but she would also be better off. In Figure 9.4, the indifference curve through B is above the indifference curve through A. This is because, as a person, she has a degree of pure impatience.

To see this, notice that when Julia’s utility is at the same level as when she has the $100 in the future, she must be on the same indifference curve, that is, the one going through A. You can see that on that indifference curve at B′, her consumption is much lower than $100. For the indifference curves shown in Figure 9.4, she values $100 later the same as she values half that amount now (B′ is one half of B).

Question 9.3 Choose the correct answer(s)

Figure 9.3 depicts Julia’s indifference curves for consumption in periods 1 (now) and 2 (later). Based on this information, which of the following statements are correct?

  • The slope of the indifference curve is the marginal rate of substitution between the consumption in the two periods.
  • The marginal return to consumption in period 1 is higher at E than at C.
  • Julia’s consumption is more equal across the two periods at C than at E. Therefore, she prefers consumption choice C to E.
  • Consuming exactly the same amount in the two periods is Julia’s most preferred choice.
  • In order to stay on the same indifference curve, the change in utility due to a marginal change in consumption now must be precisely offset by the change in utility due to the change in consumption later.
  • At E, Julia is consuming more now than at C. Due to diminishing marginal returns to consumption, Julia’s marginal return to consumption now is lower at E than at C.
  • The two points are on the same indifference curve. Therefore, she is indifferent between the two.
  • This depends on the interest rate (one plus interest rate is the slope of the feasible frontier) and the shape of the indifference curves. Julia’s preferred choice is at F, where the consumption in the two periods is not necessarily equal.

9.5 Borrowing allows smoothing by bringing consumption to the present

How much will Julia borrow? If we combine Figures 9.2 and 9.3, we will have the answer. As in the other examples of a feasible set and indifference curves, Julia wishes to get to the highest possible indifference curve but is limited by her feasible frontier. The highest feasible indifference curve when the interest rate is 10% will be the one that is tangent to the feasible frontier, shown as point E in Figure 9.5. This means that Julia borrows just enough so that:

We know that:


If we subtract 1 from both sides of this equation, we have:

Here, Julia chooses to borrow and consume $56 and repay $62 later, leaving her $38 to consume later.

Now consider how much she would borrow if she had to pay not 10%, but the 78% that was the average among the Chambar farmers. Figure 9.5 shows that, as before, finding the point of tangency between the new feasible frontier given by the 78% interest rate and one of Julia’s indifference curves, she will choose point G, meaning that she will borrow much less—$35—to consume now, paying $62 with interest, and having $38 to consume later.

The higher ‘price’ of moving consumption forward in time means two things:

  • She is less well off than with the lower interest rate: Compare her two indifference curves (one through E, the other through G).
  • She will borrow less and consume less now: $35 rather than $56.

In the example we considered above, her consumption later does not change. But, depending on the shape of her indifference curves, it could be lower or higher. With the higher interest rate, she is less well off, so this would tend to push down her consumption later. But the higher interest rate makes it costlier to bring consumption forward, which would tend to push up her consumption later.

Use the analysis in Figure 9.5 to see how Julia will choose consumption when the interest rate is 10% and when it is 78%.

Figure 9.5 Moving consumption over time by borrowing.

Julia’s feasible frontier

Julia wishes to get to the highest indifference curve but is limited by her feasible frontier.

Julia’s best option

When the interest rate is 10%, the highest attainable indifference curve is the one that is tangent to the feasible frontier shown as point E.


At this point, MRS = MRT.

The decision to borrow

At point F, her discount rate, , exceeds r, the interest rate, so she would like to bring consumption forward in time. This means that the benefits to her of bringing some consumption forward to the present () are greater than the costs (r), so she will borrow more to finance current consumption. Similar reasoning eliminates all points except E on the feasible frontier.

An increase in the interest rate

If the interest rate at which she can borrow increases, the feasible set gets smaller.

The effect of a higher interest rate

The best Julia can do now is to borrow less ($35 instead of $56), as shown by point G.

Question 9.4 Choose the correct answer(s)

Figure 9.5 depicts Julia’s choice of consumptions in periods 1 and 2. She has no income in period 1 (now) and an income of $100 in period 2 (later). The current interest rate is 10%. Based on this information, which of the following statements are correct?

  • At F, the interest rate exceeds Julia’s discount rate (degree of impatience).
  • At E, Julia is on the highest possible indifference curve, given her feasible set.
  • E is Julia’s optimal choice, as she is able to completely smooth out her consumption over the two periods and consume the same amount.
  • G is not a feasible choice for Julia.
  • At F, the slope of the indifference curve is steeper than that of the feasible frontier. Therefore, Julia’s discount rate exceeds the interest rate.
  • E is on the highest feasible indifference curve because any higher indifference curves would not touch the feasible frontier.
  • At E, Julia consumes 56 in period 1 and 38 in period 2.
  • G is in Julia’s feasible set. She does not choose it because it is not the optimal choice (it is on a lower indifference curve).

9.6 Storing or lending allows smoothing and moving consumption to the future

Now think about Marco, an individual otherwise identical to Julia, but facing a very different situation. Marco has wealth of $100 but does not (yet) anticipate receiving any income later.

By identical, we mean that Marco’s preferences between consumption now and later are the same as Julia’s. For example, in Figure 9.4 we showed a hypothetical indifference curve for Julia if she had $100 now. This is Marco’s reservation indifference curve in Figure 9.6.

Marco and Julia have the same degree of pure impatience but are in very different situations. Julia wishes to bring forward some consumption; Marco could use all of his $100 to buy goods to consume now, but as we have seen, this would probably not be the best he could do given the circumstances. In order to smooth his consumption over time, he wishes to move some consumption to the future.

Marco’s options for smoothing: Storing

Marco could do this by just putting some of his wealth in cash in a drawer, not spending it now, and having it later. We assume that his $100 will not be stolen and that $100 will purchase the same amount of goods now and later because there is no inflation (that is, the price level in the economy doesn’t rise).

In Figure 9.6, we see that Marco’s endowment is on the horizontal axis, as he has $100 available now. His reservation indifference curve includes the point $100 on the horizontal axis.

Figure 9.6 analyses Marco’s decision. The dark line shows Marco’s feasible frontier if he just ‘stores’ his wealth in cash in the drawer, and the dark shaded area shows his feasible set. The frontier shows that, for every dollar that Marco stores, he will have a dollar later—for example, if he stored $50 he could consume $50 of his wealth now and $50 later. Thus, the marginal rate of transformation (MRT) of current consumption into future consumption is just 1.

Figure 9.6 Smoothing consumption by storing.

Marco’s preferences

Marco’s reservation indifference curve goes through his endowment.

Marco’s preferences

Indifference curves to the right of Marco’s reservation curve indicate higher levels of utility.

Marco’s feasible frontier

With storage, there is a one-to-one trade-off between consumption now and consumption later.

Marco’s decision to store

Point H on Marco’s indifference curve denotes the amount of storage that he will choose.

In Figure 9.6, some part of Marco’s feasible frontier lies above and to the right of his reservation indifference curve, so he can do better by storing. If storing were the only option, he would definitely store some of his $100.

In the figure we see that he stores less than half, so he ends up consuming more now than later. This means that Marco, like Julia, has some degree of pure impatience. If this were not the case, he would store half of his endowment and have the same levels of consumption now and later.

Marco’s options for smoothing: Lending

A better plan, if Marco could find a trustworthy borrower who would repay for sure, would be to lend some of his wealth. If he did this and could be assured of repayment of (1 + r) for every $1 lent, then he could have feasible consumption of 100 × (1 + r) later, or any of the combinations along his new feasible frontier. The light line in Figure 9.7 shows the feasible frontier when Marco lends at 20%. By lending, Marco has raised the marginal rate of transformation of current spending into future spending. With storing it was just 1. Now it is 1.2.

As you can see from Figure 9.7, Marco’s feasible set is now expanded by the opportunity to lend money at interest, compared to storing the cash (putting it in his drawer). Anything that expands a person’s feasible set so that the old feasible set is entirely inside the new one must allow that person to be better off. Marco is able to reach a higher indifference curve by lending rather than storing.

As we shall see in Unit 10, there are a variety of financial instruments in a contemporary economy that Marco can use to shift consumption to the future by lending—such as term deposits or bonds issued by companies or by the government. Note that, in recent years, returns of 20%, as in Figure 9.7, have been very unusual indeed.

Figure 9.7 Smoothing consumption by storing and lending.

Marco’s decision to lend

The light line shows the feasible frontier when Marco lends at 20%.

The effect of the decision to lend

Marco is now able to reach a higher indifference curve.

But how much will Marco lend? Like Julia, he will seek the highest feasible indifference curve by finding the point of tangency between the indifference curve and the feasible frontier. This is point J, at which Marco has equated his MRS between consumption now and in the future to the MRT, which is the cost of moving goods from the present to the future.

In the example, the amount Marco lends does not change. But it could be lower or higher. When he lends, he is better off, so this would tend to push up his consumption now and push down his lending. But when he can earn interest, this increases his return from postponing consumption. This would tend to push up his lending and raise his consumption later. The case in the diagram assumes that these cancel out, leaving lending and consumption now unchanged.

Exercise 9.2 Marco’s feasible frontier

As we did with Julia, we construct Marco’s feasible frontier under storing or lending by finding all the combinations of consumption now and in the next period, given his endowment and the interest rate.

  1. Complete the table below, using the information given. Round your answers to the nearest dollar.
  2. Using your completed table, draw a diagram similar to Figure 9.7, showing the feasible frontier, consumption, and lending options.

Point on the feasible frontier Consumption now Consumption later Amount stored or lent (excluding interest)
Calculation = Income now – Amount stored or lent = Amount stored
or = Amount lent including interest on the loan
or = (1 + r) × Amount lent
Endowment point
(100, 0) 100 0 0
Store money in a drawer
91 9 9
Lend at an interest rate of 20%
(56, 53) 56 (1 + 0.2)(100 − 56) = 53 44


Question 9.5 Choose the correct answer(s)

Figure 9.7 depicts Marco’s choice of consumption in periods 1 (now) and 2 (later). He has $100 in period 1 and no income in period 2. Marco has two choices: he can store the money that he does not spend in period 1, or he can lend the money he does not consume at an interest rate of 20%. Based on this information, which of the following statements are correct?

  • With storage, if Marco consumes $68 in period 1, he can consume $32 in period 2.
  • With lending, if Marco consumes $68 in period 1, he can consume $35 in period 2.
  • The marginal rate of transformation is higher when storing than when lending.
  • Marco will always be on a higher indifference curve when lending than when storing.
  • Under storage, Marco’s consumption in both periods must sum to $100.
  • He lends $32, which then increases in value by 20% to $38.40.
  • The MRT is 1 when storing, and 1.2 when lending.
  • The feasible frontier for lending is higher than the feasible frontier for storing, at any positive level of storing.

9.7 Mutual gains and conflicts over their distribution in the credit market

In the initial situation, Julia and Marco would both get $100 eventually, but time creates a difference. In the present, Marco’s wealth, narrowly defined, is $100. Julia’s wealth is zero.

Marco and Julia’s indifference curves, and hence their pure impatience, are identical. They differ according to their situation, not their preferences. Marco’s reservation indifference curve is superior to Julia’s (farther away from the origin) because he has wealth now, and she has the same amount, but later. Julia borrows because she is poor in the present, unlike Marco, which is why she is more impatient than him. She wants to smooth her consumption by bringing some buying power to the present.

Julia and Marco are on opposite sides of the credit market

The fact that Marco is in exactly the opposite situation—he is looking for ways to move some consumption to the future—explains why they can mutually benefit, Marco by lending and Julia by borrowing. We are not assuming that they are borrowing and lending directly to each other. Rather, they are borrowing and lending on the same market.

The solid lines in Figure 9.8 show the borrowing opportunities for Julia and lending opportunities for Marco, both measured by their feasible frontiers.

The feasible frontiers of the two both have a slope of (1 + r). For Julia, the cost of moving $1 from the future to the present by borrowing is 1 + r, while for Marco the gain from moving $1 from the present to the future by lending is also 1 + r. They face the same ‘price’ of moving consumption in time, but they are moving their buying power in different directions.

Remember, in this unit what we call the ‘slope’ will always be a positive number, even though the line slopes downwards.

This is why Marco’s feasible frontier is uniformly outside Julia’s; he has more choices open to him than she does. Because they have identical indifference curves, we know that he will be able to enjoy a higher level of utility than Julia.

Figure 9.8 On opposite sides of the market: An increase in the interest rate improves Marco’s welfare and reduces Julia’s.

Julia’s feasible frontier

The dark red line shows Julia’s feasible frontier when the interest rate is 20%.

Marco’s feasible frontier

The bright red line shows Marco’s feasible frontier when the interest rate is 20%.

Effect of an interest rate rise on Julia’s frontier

When the interest rate rises to 78%, Julia’s feasible set shrinks.

Effect of an interest rate rise on Marco’s frontier

When the interest rate rises to 78%, Marco’s feasible set expands.

Figure 9.8 also shows the effect of an increase in the rate of interest from r = 0.20 to r = 0.78. The increase in the rate of interest makes both feasible frontiers steeper, but this:

  • Moves Marco’s feasible frontier outwards: Expanding his set of choices.
  • Moves Julia’s feasible frontier inwards: Shrinking her set of choices.

Let’s return to how Marco differs from Julia. They have identical preferences, but:

  • Marco starts with wealth while Julia starts with nothing: Julia has the guarantee of a similar asset later, but this puts the two on opposite sides of the credit market.
  • Because of this difference in their situation, they can both benefit by participating in the credit market, Julia by borrowing and Marco by lending.
  • Because Marco’s feasible frontier is entirely outside Julia’s, he can end up on a higher indifference curve than can Julia.
  • Because the cost of moving consumption forward in time by borrowing (the rate of interest) is the same as the gain to Marco by postponing his consumption (by lending), they have a conflict of interest over how the mutual gains from exchange are shared.

Real and nominal interest rates: who benefits from inflation?

real interest rate
The price of bringing some real spending power forward in time. See also: nominal interest rate.

We have thus far referred simply to ‘the interest rate’. But in relating it so explicitly to the price of future consumption, we have implicitly been using what economists call the real interest rate—since what Julia cares about is her loss of real spending power, that is, what she can buy in the future taking account of inflation.

nominal interest rate
The price of bringing some spending power (in dollars or other nominal terms) forward in time. The policy rate and the lending rate quoted by commercial banks are examples of nominal interest rates. See also: real interest rate, interest rate, Fisher equation.
Fisher equation
The relation that gives the real interest rate as the difference between the nominal interest rate and expected inflation: real interest rate = nominal interest rate – expected inflation.

Economists contrast this to the nominal interest rate, which is the rate that is typically actually paid on loans. When the price of goods and services is rising—that is, if there is a positive inflation rate—the nominal interest rate overstates the real interest rate.

To take account of inflation when analysing borrowing and lending, we must use the real interest rate because it represents how many goods in the future one gets for the goods not consumed now. The Fisher equation, named after Irving Fisher (1867–1947), summarizes the relationship between the real and nominal interest rates, and inflation:

Whether you lose or benefit from inflation depends on which side of the credit market you are on. As we have seen, Julia the borrower and Marco the lender have a conflict about the real interest rate: she benefits from a fall in the interest rate and he benefits from a rise. So they also have differing perspectives on inflation, because if prices rise before Julia repays her loan, a lender like Marco would find that he can buy less with the repayment than would have been the case if there were zero inflation. She benefits from a fall in the real interest rate because of inflation; he loses out.

More precisely, the real interest rate measures the buying power of the repayment of a loan at the stipulated nominal interest rate, taking account of the prices that exist when the loan is repaid. To see what this means, let’s consider a situation in which Julia were to borrow $50 directly from Marco with a repayment of $55 next year. The nominal interest rate for this loan contract between them is 10%. But if next year’s prices were 6% higher than this year’s (6% inflation rate), then what Marco could buy with the repayment is not 10% more than he could have bought with the sum he loaned to Julia, but instead only 4%. The real interest rate is 4%.

Question 9.6 Choose the correct answer(s)

The following table shows the nominal interest rate and the annual inflation rate (the GDP deflator) of Japan in the period 1996–2015 (Source: World Bank).

  1996–2000 2001–2005 2006–2010 2011–2015
Interest rate 1.5% 1.4% 1.3% 1.2%
Inflation rate –1.9% –0.9% –0.5% 1.6%

Based on this information, which of the following statements are correct?

  • The real interest rate in 1996–2000 was –0.4%.
  • Japan’s real interest rate has been rising consistently over this period.
  • Japan’s real interest rate turned from being positive to negative during the period.
  • The real interest rate has been falling faster than the nominal interest rate.
  • Using the Fisher equation, the real interest rate in 1996–2000 was 1.5 – (–1.9) = 3.4%.
  • The real interest rates for the four periods are: 3.4%, 2.3%, 1.8%, and –0.4% respectively. Therefore the real interest rate has been falling consistently over the period.
  • It was positive in the first three periods and turned negative in 2011–2015.
  • The decline in the real interest rate each year is larger than the decline in the nominal interest rate because the inflation rate was also rising.

Exercise 9.3 Lifetime income

Consider an individual’s income over his or her lifetime, from leaving school to retirement. Using the concepts in this unit, explain in words how an individual may move from a situation like Julia’s to one like Marco’s over the course of their lifetime (assume that their pure impatience remains unchanged over their lifetime).

9.8 Borrowing may allow investing: Julia’s best hope

Like Julia in our model, payday borrowers in New York often buy groceries or clothes for their children with their borrowed funds; farmers in Chambar also often borrow for purposes of consumption, for example, to pay for a wedding. But both the Chambar farmers and New York payday borrowers sometimes use the borrowed funds for an investment. For the Pakistani farmers, this could be the purchase of equipment that would improve the crop yield.

An asset that a borrower pledges to a lender as a security for a loan. If the borrower is not able to make the loan payments as promised, the lender becomes the owner of the asset.

Now suppose that Julia is considering becoming a Lyft driver and to qualify needs to make some cosmetic repairs on her brother’s car that she will drive. She cannot use the car as collateral (it is not hers), so she finds it difficult to get a conventional loan. She goes to a payday lender, who, as in the example above, will charge her an interest rate of 78%. Figure 9.9 shows Julia’s feasible set and frontier based on borrowing at this rate.

Julia has a new option—she can borrow and then split how much she has borrowed between consuming some now and investing the rest. This is how she does her planning:

  • Take some of the $56 that she can borrow and invest this in fixing up the car.
  • The more she spends fixing up the car, the more money she will make as a driver, so she now has a new feasible frontier.

Suppose it is the case that every dollar Julia spends on the car will result in $3 more in income next year (that is, a rate of return of 200%). With this investment, she can move along the new dashed feasible frontier.

To see the full range of her new options, if she invested the entire $56 (so that she would have no consumption now), she would have $168 (3 × 56) next year. All the points on the dashed feasible frontier with investment are now open to her. The slope of the feasible frontier with investment is 3, which is the ratio of income later to amount invested. The steeper the slope is, the better for Julia. This slope is the marginal rate of transformation of current investment into future income.

Figure 9.9 Options for the individual (Julia) who starts without assets but can borrow and invest.

Julia’s options

She can borrow at an interest rate of 78% and can also choose to invest some of her income with a return of 200%. The dotted line shows her feasible frontier when she chooses to borrow and invest.

How much will Julia invest?

She will use the same rule that she used in deciding how much to borrow when there was no option to invest. She will find the highest feasible indifference curve by finding the tangency of an indifference curve and the feasible frontier, or what is the same thing, equating the MRT (slope of the feasible frontier) with the MRS (slope of the indifference curve.)

Julia’s optimal choice

Doing this, Julia chooses point I in the figure. How does this work out for her? Having borrowed the maximum—$56—she invests $21 and consumes $35 now. The investment of $21 will yield her an income of $63 later.

The investment opportunity has greatly increased Julia’s wellbeing. She consumes the same amount now that she did when only the borrowing opportunity was available—$35—but she can now consume $63 later, rather than only $38. Note that she will only invest if she has an investment project with a rate of return higher than 78%—the rate of return has to be higher than the borrowing rate in order to expand her feasible set.

In our example, Julia consumes the same amount now under the borrowing only and borrowing and investment options; her current consumption could be either greater than or less than in the case without the investment opportunity. What is certain is that she is better off with the investment opportunity because her feasible set is expanded.

We can thus contrast three situations in which Julia might have found herself:

  • Exclusion from the credit market: She is unable to get a loan of any kind. Her feasible set is just a single point (A) in Figure 9.9. Many would-be borrowers—those without collateral, for example—are simply excluded from borrowing at any rate of interest. Her reservation indifference curve indicates her wellbeing in that situation.
  • Borrowing: Now she has a larger feasible set, including point A, but also all the other points in the solid line in Figure 9.9, including point G—her choice when she can borrow but not invest.
  • Borrowing and investing: She now has the opportunity to bring buying power forward in time to the present (by borrowing) and then shifting some of it back in time while tripling its value (by investing), enabling her to achieve point I.

Question 9.7 Choose the correct answer(s)

Figure 9.9 depicts two possible feasible frontiers for Julia, who has no income in period 1 (now) and $100 in period 2 (later). The solid line (option 1) shows her feasible frontier if she borrows at an interest rate of 78%. The dotted line shows her feasible frontier if she borrows at an interest rate of 78% and can invest for a return of 200% (option 2). Based on this information, which of the following statements are correct?

  • When borrowing only, Julia is worse off than at her initial endowment (point A) because of the high interest rate.
  • The consumption choice G can only be attained under option 1.
  • If the interest rate for borrowing increases to 100%, ceteris paribus the feasible frontiers become steeper and the vertical axis intercept under option 2 is now $150.
  • If the return on investment increases to 250%, ceteris paribus the vertical axis intercept under option 2 is now $200.
  • Julia is on a higher indifference curve at G than at her endowment point. Therefore, she is better off when borrowing.
  • G is in the feasible set of options 1 and 2, so it is a possible choice under both options. However, G is only optimal under option 1.
  • With an interest rate of 100%, Julia can borrow a maximum of $50 in period 1, so her maximum consumption in period 2 is 50 + 2(50) = $150.
  • With a return of 250%, Julia’s maximum consumption in period 2 is 56 + 2.5(56) = $196.

9.9 Balance sheets: Assets and liabilities

Anything of value that is owned. See also: balance sheet, liability.
Anything of value that is owed. See also: balance sheet, asset.
net worth
Assets less liabilities. See also: balance sheet, equity.
An entity is this if the value of its assets is less than the value of its liabilities. See also: solvent.

A balance sheet summarizes what the household, bank, or firm owns and what it owes to others. The things you own (including what you are owed by others) are called your assets, and the debts you owe others are called your liabilities (to be liable means to be responsible for something, in this case to repay your debts to others). The difference between your assets and your liabilities is called your net worth. The relationship between assets, liabilities, and net worth is shown in Figure 9.10.

If the value of assets is below that of liabilities, the net worth of the entity (household, firm, or bank) is negative and it is insolvent.

Figure 9.10 A balance sheet.

When the components of an equation are such that by definition, the left-hand side is equal to the right-hand side, it is called an accounting identity, or identity for short. The balance sheet identity states:

To understand the concept of net worth, which is what makes the left- and right-hand sides balance by definition, we can turn the identity around by subtracting liabilities from both sides so that:

The composition of the balance sheets of banks and non-financial companies look very different. Figure 9.11 illustrates the relationship between liabilities and net worth in the case of a bank—Barclays—and a motor vehicle company, Honda. It is immediately evident that the bank is a very debt-heavy entity compared to the non-financial firm.

Figure 9.11 Liabilities and net worth (Barclays and Honda).

Barclays Bank. 2017. Barclays PLC Annual Report 2017. Honda Motor Co. 2013. Annual Report.

Balance sheets help us to understand the relationships between households and banks in the economy. Bank deposits make up part of the typical household’s assets and they appear on the liability side of the balance sheet of banks in the economy. Another typical asset of a household is its house. Unless the household owns the house outright, the household has a liability as well as an asset—the liability is the mortgage. The mortgage, in turn, is an asset of the bank.

global financial crisis
This began in 2007 with the collapse of house prices in the US, leading to the fall in prices of assets based on subprime mortgages and to widespread uncertainty about the solvency of banks in the US and Europe, which had borrowed to purchase such assets. The ramifications were felt around the world, as global trade was cut back sharply. Goverments and central banks responded aggressively with stabilization policies.

In Unit 10, we return to the balance sheets of households and banks in the global financial crisis. For some households, when house prices fell, their assets were worth less than the mortgage (that is, their liability—what they owed on the house). Households defaulted on their mortgage payments.

Many banks—with a balance sheet similar in structure to that of Barclays in Figure 9.11—were vulnerable to their net worth being ‘wiped out’ by a fall in the value of their assets. When net worth is a tiny fraction of the size of the balance sheet, a small percentage change in the value of the bank’s assets can reduce it below the unchanged value of its debts (its liabilities). Given that mortgages and other assets based on mortgages accounted for a substantial part of banks’ assets, when house prices fell and households defaulted on their mortgages, this reduced the banks’ assets and threatened to reduce the individual bank’s net worth below zero.

Banks were insolvent and as we shall see, governments stepped in to bail them out.

Borrowing, lending, and net worth

In the bathtub analogy in Figure 9.1, the water in the bathtub represents wealth as accumulated savings and is the same as net worth. As we saw, net worth or wealth increases with income (inflow to the bathtub), and declines with consumption and depreciation (outflow).

But your wealth or net worth does not change when you lend or borrow. This is because a loan creates both an asset and a liability on your balance sheet; if you borrow money, you receive a bank deposit or cash as an asset, while the debt is an equal liability.

In our example, Julia starts off with neither assets nor liabilities and a net worth of zero, but on the basis of her expected future income a bank lends her $56 at an interest rate of 10% (point E in Figure 9.5). At this time, her asset is the $56 in the bank deposit that she is holding, while her liability is the loan that she must pay back later. We record the value of the loan as $56 now, since that is what she received for getting into debt (her liability rises to $62 later only once interest has been added). This is why taking out the loan has no effect on her current net worth—the liability and the asset are equal to one another, so her net worth remains unchanged at zero. In Figure 9.12, this is recorded in her balance sheet under the heading ‘Now (before consuming)’.

She then consumes the $56—it flows out through the bathtub drain, to use our earlier analogy. Since she still has the $56 liability, her net worth falls to –$56. This is recorded in Figure 9.12 in her balance sheet under the heading ‘Now (after consuming)’.

Later, she receives income of $100 deposited in her bank account (an inflow to the bathtub). Also, because of the accumulated interest due, the value of her loan has risen to $62. So her net worth becomes $100 – $62 = $38. Again, we suppose that she then consumes the $38, leaving her with $62 to pay off her debt of $62. At this point, her net worth falls back to zero. The corresponding balance sheets are also shown in Figure 9.12.

Now—before consuming

Julia's assets Julia's liabilities
Bank deposit $56 Loan $56

Net worth = $56 − $56 = $0

Now—after consuming

Julia's assets Julia's liabilities
Bank deposit 0 Loan $56

Net worth = −$56

Later—before consuming

Julia's assets Julia's liabilities
Bank deposit $100 Loan $62

Net worth = $100 − $62 = $38

Later—after consuming

Julia's assets Julia's liabilities
Bank deposit $62 Loan $62

Net worth = 0

Figure 9.12 Julia’s balance sheets.

Question 9.8 Choose the correct answer(s)

The following diagram depicts Julia’s choice of consumption in periods 1 (now) and 2 (later) when the interest rate is 78%. She has no income in period 1 and an income of $100 in period 2. Her consumption choice is shown by G. Based on this information, which of the following statements regarding Julia’s balance sheet are correct?

Figure 9.13 Julia’s consumption choices.

  • The asset after borrowing but before consumption in period 1 is $56.
  • The net worth after consumption in period 1 is $0.
  • The liability before consumption in period 2 is $35.
  • The asset after consumption but before repaying the loan in period 2 is $62.
  • The asset after borrowing but before consumption in period 1 is $35.
  • The net worth after consumption in period 1 is –$35, which is what she borrowed.
  • The liability before consumption in period 2 is $62, which is the principal plus interest of her loan of $35 in period 1.
  • Her income in period 2 is $100, of which she consumes $38, leaving $62 before she repays the loan.

9.10 Credit market constraints: Another principal–agent problem

Lending is risky

Up until now, we have said little about the elephant in the room—lending is a risky activity for a bank or money lender. A loan is made now and must be repaid in the future. Between now and then, unanticipated events beyond the control of the borrower can occur.

If the crops in Chambar, Pakistan were destroyed by bad weather or disease, the moneylenders would not be repaid, even though the farmers worked hard. The obsolescence of the skill you have invested in using your student loan is an unavoidable risk and will mean the loan may not be repaid.

The greater the risk of default due to unavoidable events, the greater the interest rate set by a bank or a moneylender. This is one explanation for why an interest rate of 78%, as is the case in Chambar, is not highly profitable. Two other reasons were noted in the introduction:

  • The moneylenders themselves face a high cost of borrowing: The JS Bank lends them money to lend to farmers at an interest rate of 32%.
  • The moneylenders compete: This limits the profits they are able to make.

Conflicts of interest, and information problems

But lenders face two further problems. When loans are taken out for investment projects, the lender cannot be sure that a borrower will exert enough effort to make the project succeed. Remember, if the borrower has not put any of her own money into the project, it is the lender, not the borrower, who loses money if the project fails and the loan is not repaid.

Moreover, often the borrower has more information than the lender about the quality of the project and its likelihood of success.

These problems arise in turn from a difference (or conflict) of interest between the borrower and lender, and from the difference between the information the borrower and the lender have about the borrower’s project and actions. The problems impose costs of monitoring and loan enforcement that will push up the interest rate on loans.

If the project doesn’t succeed because the borrower made too little effort or because it just wasn’t a good project, the lender loses money. If the borrower were using only her own money, it is likely that she would have been more conscientious or maybe not engaged in the project at all.

The borrower may decide to use the borrowed funds for a much riskier project than the one that she told the lender she would use it for. To illustrate this (with an extreme example), she could simply buy lottery tickets with the money she has borrowed—if one of them pays off, she is rich; if not, the lender does not get repaid.

principal–agent relationship
This is an asymmetrical relationship in which one party (the principal) benefits from some action or attribute of the other party (the agent) about which the principal’s information is not sufficient to enforce in a complete contract. See also: incomplete contract. Also known as: principal–agent problem.

The relationship between the lender and the borrower is a principal–agent problem similar in many ways to the relationship between the employer and employee studied in the previous unit. The lender is the ‘principal’ and the borrower is the ‘agent’.

The principal–agent problem between borrower and lender is also similar to the ‘somebody else’s money’ problem discussed in Unit 6. In that case, the manager of a firm (the agent) makes decisions about the use of the funds supplied by the firm’s owners (the principals), but they cannot contractually require the manager to act in a way that maximizes their wealth, rather than pursuing her own objectives.

Incomplete contracts

In the case of borrowing and lending, it is often not possible for the lender (the principal) to write a contract that ensures a loan will be repaid by the borrower (the agent). The reason is that it is impossible for the lender to ensure by contract that the borrower will use the funds in a prudent way and repay according to the terms of the loan.

The table in Figure 9.14 compares two principal–agent problems.

Actors Conflict of interest over Enforceable contract covers Left out of contract (or unenforceable) Result
Labour market (Unit 6) Employer
Wages, work (quality and amount) Wages, time, conditions Work (quality and amount), duration of employment Effort under-provided; unemployment
Credit market (Unit 9) Lender
Interest rate, conduct of project (effort, prudence) Interest rate Effort, prudence, repayment Too much risk, credit constraints

Figure 9.14 Principal–agent problems: The credit market and the labour market.

Lenders will attempt to secure repayment of a loan through legal measures but this will often be difficult if the borrower is poor or declares bankruptcy because they are insolvent. In the introduction to this unit, we reported an example of a method of improving compliance in car loan repayments—companies install devices that disable the ignition of the car if the repayments are not made as required.

If legal methods fail, lenders may use illegal ones, such as threatening physical violence.

The role of collateral in lending

An individual’s own investment in a project. This is recorded in an individual’s or firm’s balance sheet as net worth. See also: net worth. An entirely different use of the term is synonymous with fairness.

One response of the lender to the conflict of interest in the credit market is to require the borrower to put some of her wealth into the project (this is called equity). The more of the borrower’s own money that is invested in the project, the more closely aligned her interests are with those of the lender. Another common response is to require the borrower to set aside property that will be transferred to the lender if the loan is not repaid (this is called collateral).

Collateral is used in loans for houses (called mortgages) and for cars. For many people, these are the only large loans they can get, and that is because of the collateral—the house, or the car reverts to the lender if repayments are not made.

The pawnbroker is a common example of collateral in small-scale lending and borrowing that has existed for thousands of years. The pawnbroker, found today on shopping streets under the slogan ‘Cash converter’ or similar, extends a loan to the borrower with a date and amount of repayment specified. And the borrower turns over some item of his or her property to the pawnbroker, which will be returned to the borrower when the loan is repaid. Items commonly lodged with a pawnbroker because they can easily be sold include jewelry, computers and other electronic equipment, cameras, or valuable household items.

A loan with collateral is called a secured loan because, as long as the collateral (the house or the pawned item) can readily be sold for more than the amount of money owed, the lender is secure. With a secured loan, the lender does not run any risk.

Equity or collateral reduces the conflict of interest between the borrower and the lender. The reason is that, when the borrower has some of her money (either equity or collateral) at stake:

  • She has a greater interest in working hard: She will try harder to make prudent business decisions to ensure the project’s success.
  • It is a signal to the lender: It signals that the borrower thinks that the project is of sufficient quality to succeed.

Credit rationing and inequality

credit rationing
The process by which those with less wealth borrow on unfavourable terms, compared to those with more wealth.
A description of individuals who are unable to borrow on any terms. See also: credit-constrained.
A description of individuals who are able to borrow only on unfavourable terms. See also: credit-excluded.

But there is a hitch. If the borrower had been wealthy, she could either have used her wealth as collateral and as equity in the project, or she could have been on the other side of the market, lending money. Often the reason why the borrower needs a loan is that, like Julia, she is not wealthy. As a result, she may be unable to provide enough equity or collateral to sufficiently reduce the conflict of interest and hence the risk faced by the lender, and the lender refuses to offer a loan.

Adam Smith had credit rationing in mind when he wrote: ‘Money, says the proverb, makes money. When you have got a little it is often easy to get more. The great difficulty is to get that little.’ Adam Smith. 1776. ‘Of the profits of stock’. In An Inquiry into the Nature and Causes of the Wealth of Nations.

This is called credit rationing—those with less wealth borrow on unfavourable terms compared with those with more wealth or are refused loans entirely.

Borrowers whose limited wealth makes it impossible to get a loan at any interest rate are termed credit-excluded. Those who borrow, but only on unfavourable terms, are termed credit-constrained. Both are sometimes said to be wealth-constrained, meaning that their lack of wealth limits their credit market opportunities.

The relationship between wealth and credit is summarized in Figure 9.15.

Figure 9.15 Wealth, project quality, and credit.

The exclusion of those without wealth from credit markets or their borrowing on unfavourable terms is evident in these facts:

  • In a survey, one in eight US families had their request for credit rejected by a financial institution: The assets of these credit-constrained families were 63% lower than the unconstrained families. ‘Discouraged borrowers’ (those who did not apply for a loan because they expected to be rejected) had even lower wealth than the rejected applicants.
  • Credit card borrowing limits are often increased automatically: If borrowing increases in response to an automatic change in the borrowing limit, we can conclude that the individual was credit-constrained. The authors of this study suggested that approximately two-thirds of US families may be credit-constrained or excluded.3
  • Inheritance leads the self-employed to considerably increase the scale of their operations: An inheritance of £5,000 in 1981 (around $24,000 today) doubled a typical British youth’s likelihood of setting up a business.
  • Owning a house can be used as collateral: A 10% rise in value of housing assets that could be used as collateral to secure loans in the UK increases the number of startup businesses by 5%.
  • Asset-poor people in the US frequently take out short-term ‘payday loans’: In the state of Illinois, the typical short-term borrower is a low-income ($24,104 annual income) woman in her mid-thirties, living in rental housing, borrowing between $100 and $200, and paying an average annual rate of interest of 486%.
  • Poor and middle-income Indian farmers could substantially raise their incomes if they did not face credit constraints: Not only do they generally underinvest in productive assets, but the assets they hold are biased towards those they can sell in times of need (bullocks) and against highly profitable equipment (irrigation pumps), which have little resale value.4

Question 9.9 Choose the correct answer(s)

Which of the following statements regarding the principal–agent problem are correct?

  • A principal–agent problem exists in the credit market due to a positive possibility of the principal not being repaid.
  • The principal–agent problem can be resolved by writing a binding contract for the borrower to exert full effort.
  • One solution for the principal–agent problem in the credit market is for the borrower to provide equity.
  • The principal–agent problem leads to credit rationing in the credit market.
  • A principal–agent problem exists in the credit market due to the asymmetric information regarding the borrower’s effort or the quality of the project.
  • The principal–agent problem exists because one cannot write a binding contract for full effort.
  • Equity implies that the agent has more to lose if the project fails, reducing the difference in the incentives between the principal and the agent.
  • This occurs because some otherwise-viable projects will not be funded owing to the principal–agent problem. In particular, those with few assets or little wealth who cannot afford to put in equity or provide collateral are more likely to be credit rationed because of the principal–agent problem.

Exercise 9.4 How Julia paid for her Christmas presents

On Christmas Day in 2014, the New York Times published an article entitled ‘Rise in Loans Linked to Cars is Hurting the Poor’. Read the article and watch the video in the article with the title: ‘No credit, no problem’.

Here are two quotes from the article:

‘The lenders argue that they are providing a source of credit for people who cannot obtain less-expensive loans from banks. The high interest rates, the lenders say, are necessary to offset the risk that borrowers will stop paying their bills.’

‘And because many lenders make the loan based on an assessment of a used car’s resale value, not on a borrower’s ability to repay that money, many people find that they are struggling to keep up almost as soon as they drive off with the cash.’

Based on the information in the article and the video:

  1. What are the loans discussed in this article used for, and are they secured (i.e. with collateral) or unsecured (i.e. without collateral)? What role, if any, is played by collateral?
  2. Does the interest rate charged depend on the wealth of the borrower? Illustrate your argument using a diagram with consumption now on the horizontal axis and consumption later on the vertical axis.
  3. In the video, Marcelina Mojica mentions that she went bankrupt (a legal procedure that can follow when a person or a business is insolvent). Using information in the article, provide a plausible explanation of why she went bankrupt, referring to the assets and liabilities in her balance sheet.

Exercise 9.5 Microfinance and lending to the poor

Read the paper ‘The Microfinance Promise’.5

The Grameen Bank in Bangladesh makes loans available to groups of individuals who together apply for individual loans, under the condition that the loans to the group members will be renewed in the future if (but only if) each member has repaid the loan on schedule.

  1. Explain how you think such an arrangement would affect the borrower’s decision about what to spend the money on, and how hard she will work to make sure that repayment is possible.
  2. Use the concepts in this section to explain how the Grameen Bank’s lending method could affect credit rationing and credit exclusion.
  3. Find evidence about whether or not microfinance has been effective in increasing investment by groups who would normally be excluded from the credit market.

Exercise 9.6 Pawn shops as a source of credit

If you want to find out more about pawn broking, this quote is taken from Susan Payne Carter and Paige Marta Skiba. 2012. ‘Pawnshops, Behavioral Economics, and Self-Regulation’. Review of Banking and Financial Law 32 (1): pp. 193-220.

Pawn broking is one of the oldest sources of credit in the world. A pawn shop offers loans in exchange for items such as jewelry which are held by the shop until the loan is repaid. Such shops are mainly used by people on low incomes. In Texas, the maximum interest rate that can be charged is 20% per month. According to a study of pawn shops in Texas, default rates are lower when items of sentimental value such as rings rather than items of equivalent resale value such as TV screens are held by the shop.

In this exercise, we will provide an economic explanation for the phenomenon of pawn broking.

  1. Draw a diagram with ‘Consumption now’ on the horizontal axis and ‘Consumption later’ on the vertical axis. Draw a feasible set, endowment, and indifference curves on this diagram, and use the diagram to explain why someone might choose to use a pawn shop.
  2. Define the term that is used for the items held by the shop (such as jewelry), and explain its role in the pawn broking business.
  3. Comment on the statement that pawn shops are ‘one of the oldest sources of credit in the world’.
  4. Suggest an explanation for the differential default rates on the type of item held by the pawn shops (You may find it useful to refer to the discussion of ‘My diet begins tomorrow’ in Unit 13 of The Economy.)

9.11 Inequality: Lenders, borrowers, and those excluded from credit markets

We can analyse inequalities between borrowers and lenders (and among borrowers) using the same Lorenz curve and Gini coefficient model that we used to study inequality among employers and employees in Unit 8, and farmers and landowners in Unit 5.

Lenders and borrowers in the Lorenz curve diagram

Here is an illustration. An economy is composed of 90 farmers who borrow from 10 lenders and use the funds to finance the planting and tending of their crops. The harvest (on average) is sold for an amount greater than the farmer’s loan, so that for every euro borrowed and invested, the farmer receives 1 + R when the crop is sold after the harvest. This is the farmer’s revenue.

Following the harvest, the farmers repay the loans with interest, at rate i. To focus on the Lorenz curve model, we simplify in this section by assuming that all of the loans are repaid and that all lenders lend the same amount to the farmers at the same interest rate. The main message would not be altered if we included the probability that loans were not repaid (as in the Chambar case study), but the mathematics would be a lot more complicated.

  • What is the total income? Since each euro invested produces total revenue of 1 + R, each farmer generates income (revenue less costs) of R.
  • How is the income divided? The lender receives an income of i for every euro lent, and so the borrower (the farmer) receives the remainder, R − i. So the lender receives a share of i/R of total output, which means that the borrower (farmer) receives what remains, which is 1 − (i/R).

Thus, if i = 0.10 and R = 0.15, then the lender’s share of total income is two-thirds and the borrower’s is one-third.

Inequality in this economy is shown by the dark-shaded area bordered by a solid line in Figure 9.16. The Gini coefficient is 0.57.

Excluded borrowers raise the Gini coefficient

In the previous sections, we showed why some would-be borrowers (those unable to post collateral or lacking their own funds to finance a project) might be excluded entirely from borrowing even if they would be willing to pay the interest rate. How does this affect the Lorenz curve and the Gini coefficient?

To explore this, imagine that 40 of the prospective borrowers are now excluded. Since they cannot borrow, they receive no income at all. For the other farmers, i and R remain unchanged.

The dashed line in Figure 9.16 shows the new situation. The new Gini coefficient is 0.70, showing an increase in inequality when the poor are excluded from the credit market.

Figure 9.16 Inequality in a borrowing and lending economy. The Gini coefficient when everyone in the population can borrow is 0.57. When 40% of would-be borrowers are excluded from the credit market, it is 0.70.

A model economy of lenders and borrowers

An economy is composed of 90 farmers who borrow from 10 lenders. Since i = 0.10 and R = 0.15, the lenders’ share of total income is two-thirds and the borrowers’ is one-third. The Gini coefficient is 0.57.

Some borrowers are credit market excluded

Suppose that 40 of the prospective borrowers are excluded. Since they cannot borrow, they receive no income at all.

Inequality increases

When some prospective borrowers are excluded, the Gini coefficient increases to 0.70.

Question 9.10 Choose the correct answer(s)

In an economy with a population of 100, there are 80 farmers and 20 lenders. The farmers use the funds to finance the planting and tending of their crops. The rate of profit for the harvest is 12.5%, while the interest rate charged is 10%. Compare the following two cases:

Case A: All farmers are able to borrow.

Case B: Only 50 farmers are able to borrow.

Based on this information, which of the following statements are correct?

  • The share of total output received by the farmers who can borrow is 25%.
  • The Gini coefficient for case A is 0.5.
  • The Gini coefficient for case B is 0.6.
  • There is a 10% increase in the Gini coefficient in case B compared to case A.
  • The farmers keep 12.5 – 10 = 2.5% of the 12.5% profit rate. This is a 2.5/12.5 = 20% share.
  • The Gini coefficient for case A is 0.6.
  • The Gini coefficient for case B is 0.66.
  • 0.66 is 10% higher than 0.6.

The credit market can provide mutual gains but perpetuates inequalities

This example illustrates the fact that one cause of inequality in an economy is that some people (like Marco) are in a position to profit by lending, just as others, like Bruno in Unit 5, are in a position to profit by employing others.

It is sometimes said that rich people lend on terms that make them rich, while poor people borrow on terms that make them poor. Our example of Julia and Marco made it clear that one’s view of the interest rate—as a cost for Julia and as a source of income for Marco—depends on one’s wealth. People with limited wealth are credit-constrained, which limits their ability to profit from the investment opportunities that are open to those with more assets.

mutual gains
An outcome of an interaction among two or more people, in which all parties are better off as a result than they would have been without the interaction (or at least some parties are better off and none are worse off).

It is also true that, in determining the rate of interest at which an individual borrows, the lender often has superior bargaining power, and so can set a rate that enables him to capture most of the mutual gains from the transaction.

Banks are not the most popular or trusted institutions. In the US, for example, 73% of people expressed ‘a great deal’ or ‘quite a lot’ of confidence in the military in 2016, exactly the same as the level a decade earlier. In contrast, in 2016, only 27% expressed a degree of confidence in banks, down from 49% a decade earlier. Surveys show that the public in Germany, Spain and many other countries hold their banks in low esteem. This has particularly been the case since the financial crisis of 2008. In Unit 10, we look at banks as economic actors in a modern economy.

Like other profit-making firms, banks are owned by wealthy people and they often transact on terms (rates of interest, wages) that perpetuate the lack of wealth of borrowers and employees. But as we saw in the Chambar case, the profitability of the lending also depends on the extent of competition among lenders. The interest rate charged by the moneylenders in Chambar would have been even higher if—as in many villages—there is only a single moneylender.

Like the labour market, the credit market provides opportunities for mutual gains

But even those who dislike banks do not think that the less wealthy would be better off in their absence, any more than that the less wealthy would benefit if firms ceased to employ workers. Access to credit is essential to a modern economy—including access of the less well off to economic opportunities—because it provides opportunities for mutual gains that occur when people can benefit by moving their buying power from one time period to another, either borrowing (moving it to the present) or lending (the opposite).

Exercise 9.7 Unpopular banks

Why do you think that banks tend to be more unpopular than other profit-making firms (Honda or Microsoft, for example)?

Exercise 9.8 Limits on lending

Many countries have policies that limit how much interest a moneylender can charge on a loan.

  1. Do you think these limits are a good idea?
  2. Who benefits from the laws and who loses?
  3. What are the likely long-term effects of such laws?
  4. Contrast this approach to helping the poor gain access to loans with the Grameen Bank in Exercise 9.5.

9.12 The credit market and the labour market

The credit and labour markets share similarities. We use a principal–agent model to describe both.

  • Principals (employers, lenders) and agents (employees, borrowers) can both benefit from transacting with each other: But they have conflicting interests over the terms of the exchange (wages and effort, interest rate and repayment).
  • Some would-be agents are unable to make a transaction: The unemployed, or those who are refused credit.

The two markets are not only similar, they are related to each other, the credit market providing the funds allowing some (but not others) to become employers in the labour market. This is shown in Figure 9.17.

Figure 9.17 The credit and labour markets shape the relationships between groups with different endowments.

A model economy

Consider an economy with wealthy individuals and employees.

Credit market excluded

Those without wealth (collateral) or insufficient wealth are excluded from the credit market.

Wealthy individuals and successful borrowers

These people can purchase capital goods so as to become employers.

Those who are not wealthy

These are employees or unemployed.

Employers hire employees on the labour market

This excludes the unemployed.

Starting at the upper left of Figure 9.17, wealthy individuals can use their wealth to purchase the capital goods to become employers and they can also lend to others. Among the less wealthy, there will be some successful borrowers who can, as a result, also become employers. Those with even less wealth cannot borrow (they are the credit market excluded or can only borrow where the house provides the collateral for the mortgage), and must seek work as employees. Employers then hire employees from among the less wealthy, with some remaining unemployed (due to the workings of the labour market that you studied in Unit 8).

Horizontal arrows (‘lend to’ and ‘hire’) indicate a principal–agent relationship. Lenders and employers are the principals in Figure 9.17; their common orange colour indicates this similarity. Agents—successful borrowers, and employees—are coloured green to distinguish them from would-be agents (credit market excluded and unemployed), who are coloured purple. You definitely do not want to be in the purple boxes. But even if you are an agent lucky enough to be in one of the green boxes, the principal can put you back in the purple box just by refusing to deal with you. This is why lenders and employers have power over borrowers and employees.

Figure 9.17 helps us understand why some people end up as principals (employers, for example), while others end up as agents (employees). If one is wealthy, one can be both a lender and an employer. There is some truth to the saying that ‘people are born into their position in the economic order’. This was literally true in some economies of the past, for example, when the position of the slave was perpetuated in the slave’s children as a matter of law.

If you want to study this topic in more detail, you can read about it in Unit 19 of The Economy, which is all about the causes and effects of economic inequality.

Something similar can occur in places where wealth is inherited from parent to child. The children of employees (who inherit little wealth) are also more likely to become the next generation’s workers than are the children of employers. The children of well-off parents in the US also tend to have high incomes when they become adults.

9.13 Conclusion

We have explained how credit markets, like labour markets, shape the relationship between groups with different levels of wealth. To do so, we began by differentiating between wealth (a stock of accumulated savings) and income (a flow affected by direct taxes and transfers). Wealth can include money, financial assets, and physical assets. A broader definition of wealth includes human capital, seen as an asset contributing to higher labour earnings.

Using the feasible set and indifference curves of our constrained choice toolkit, we have developed a model of borrowing and lending to analyse how individuals decide to allocate their consumption across time periods.

Constraint Preferences
The feasible frontier—consumption now and in the future cannot exceed one’s present and future income.

The slope of the feasible frontier is determined by the interest rate r, which affects the opportunity cost of consuming today. The marginal rate of transformation (MRT) is (1 + r), indicating that one must forgo (1 + r ) units of consumption in the future in order to consume one more unit today.
Indifference curves join together all combinations of present and future consumption that provide the same level of utility.

The slope of the indifference curves is determined by the discount rate , which reflects both a preference to smooth consumption (there are diminishing marginal returns to consumption in a given period) and pure impatience (be it due to myopia or prudence). The MRS is given by (1 + ).
$$\text{Optimal choice: MRT = MRS} \\\\ (1 + r) = (1+\rho) \\\\ r=\rho$$

While the different situations of borrowers and lenders give rise to the possibility of mutual gains from interacting in the credit market, there is a conflict of interest over how these gains are distributed. An increased interest rate expands a lender’s feasible set but shrinks that of a borrower. The lender benefits from the repayment of the loan, which is a cost to the borrower.

These conflicts of interest, along with the fact that repayment cannot be guaranteed by an enforceable contract, motivate us to model this as a principal–agent relationship in which the credit contract is incomplete: It cannot enforce a prudent use of funds and the repayment of the loan.

Putting some of one’s own wealth at stake (be it as equity in a project or collateral on a loan) means that the borrower has less incentive to misuse the funds (by taking extraordinary risks, for example) and more incentive to work to make the project succeed. Individuals with limited wealth, however, may not have access to loans because they cannot provide equity or collateral, or they can only borrow at high interest rates. This credit rationing can perpetuate inequalities as it limits the ability of less wealthy people to profit from the investment opportunities that are open to those with more assets.

9.14 Doing Economics: Credit-excluded households in a developing country

In Sections 9.10 and 9.11, we outlined the principal–agent problem in credit markets, which leads to some households being credit-constrained or credit-excluded.

In Doing Economics Empirical Project 9, we will use survey data from a developing country (Ethiopia) to identify households that face credit constraints and look at how borrowing conditions vary with household characteristics.

Go to Doing Economics Empirical Project 9 to work on this project.

Learning objectives

In this project you will:

  • identify credit-constrained and credit-excluded households using survey information
  • create dummy (indicator) variables
  • explain why selection bias is an important issue.

9.15 References

  1. Irfan Aleem. 1990. ‘Imperfect information, screening, and the costs of informal lending: A study of a rural credit market in Pakistan’The World Bank Economic Review 4 (3): pp. 329–49.  

  2. Jessica Silver-Greenberg. 2014. ‘New York prosecutors charge payday loan firms with usury’. DealBook. Updated 11 August 2014. 

  3. David Gross and Nicholas Souleles. 2002. ‘Do liquidity constraints and interest rates matter for consumer behavior? Evidence from credit card data’. The Quarterly Journal of Economics 117 (1) (February): pp. 149–85. 

  4. Samuel Bowles. 2006. Microeconomics: Behavior, Institutions, and Evolution (The Roundtable Series in Behavioral Economics). Princeton, NJ: Princeton University Press.  

  5. Jonathan Morduch. 1999. ‘The Microfinance Promise’Journal of Economic Literature 37 (4) (December): pp. 1569–1614.