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Contracting
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Abhijit
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This papercan be downloadedwithoutchargefrom the Social Science Research Network PaperCollection at http://papers.ssrn.com/paper.taf?abstract_id=306990
Massachusetts
Institute
of
Technology
Departnnent
of
Econonnics
Working
Paper
Series
Contracting
Constraints,
Credit
Markets
and
Economic
Development
Abhijit
Banerjee
Working
Paper
02-1
7
September
2001
Room
E52-251
50
Memorial
Drive
Cambridge,
MA
02142
Thispaper can be
downloaded
withoutchargefrom the Social Science ResearchNetwork
Paper Collectionat http://papers.ssrn.com/paper.taf?abstract_id=xxxxx"MASSACHUSETTSINSTITUTE OFTECHNOLOGY
Contracting
Constraints,
Credit
Markets
and
Economic
Development
Abhijit
V.
Banerjee*Department
ofEconomics,
MIT
September, 2001
Abstract
This paper begins by summarizing the micro-evidence on credit markets from a large
number
ofstudiesfrom all over the world, with the goal of identifying anumber
of stylized fcicts.We
argue that, in particular, the evidence strongly suggests that for poor people in developing countries, imperfections in the creditmarket are quantita-tivelyveryimportant.We
thenbuildasimplemodelthat explainsthe observed patterns, based on the idea that monitoring and screening borrowers have both fixed and variable costs.We
go on to build a simple dynamic model that allows us to understand what the obser-vations about the credit market imply for the evolution ofthe wealth distribution.JEL
Codes: 012, D82,D31
Kejrwords: CreditMarkets; Distribution; Growth
1
Introduction
Development
economists are, perhaps by necessity, optimistic people.One
does not
become
adevelopment
economist ifone believes that the world's poorest are doing as well as they possibly could. Indeed the premise ofthe entire field' isthat thereistalent inevery people, ifnot every person,and
if'This papergrewout alectureIgaveattheWorldCongressoftheEconometricSociety
in August2000. I
am
grateful to Philippe Aghion and Esther Duflo for their comments and MarkoTervio forhis helpwith simulations.And ofgrowth theory:
What
isconvergenceother than the hopethat thereis talentthereisone central question it has tobe
what
prevents peoplefrom
making
the best use oftheir natural talents?
There
areat least five distinct answersto this question.The
first,which
is elaborated here, is the answer from contract theory: Talent is not an apple,^ one cannot simply go to the market, sell one's talentand
expect to be paid the appropriate price.The
second is coordination failure: Talent isonlytalentif it gets to
work
withthe appropriate otherinputs.Even
Lennon
needed Paul
and George
—
had
they decided to go to the City instead, he too might have found himselfadifferent profession.^The
third is poHticaleconomy:
Governments
canand
oftendo
make
it harder for people todo
what
they are best at doing.''The
fourth islearning: Peoplemay
notknow
what
they ought to be doing,and
evenwhen
theydo
the rest of the worldmay
not appreciate them. For example, a growingbody
ofevidenceshows
that farmers are often ignorant or suspicious of
more
rewarding cropsand
better seeds.^
The
final answercomes from
what
hascome
to be called behavioral economics: Peoplemay
not always seek out the best options because they are heldback
by
psychological constraints or social norms.^The
factthat thissurveyconcentrateson
the contract theoreticargument
should notbe interpretedasevidenceforitsprimacy.
But
it istheargument
that has received the
most
elaboration over the last decade or so,and
the onethat bestmatches
thecompetenciesofthe present author. Itistherefore the appropriate topic for a survey like this.^Acontract theoristwould probably sayan appleis not an appleeither
—
they can bestaleor fresh, sweet or sour. Ifyou had alotofapples to sell, you wouldprobably want
to investin areputation for sellingonly freshand sweetapples.
'There isalongtraditionin development economicsofmodels
thatemphasize coordi-nation failuresgoing back at least to Paul Rosenstein-Rodan (1943) and Ragnar Nurkse (1953). See Murphy, Shleifer and Vishny (1989) for a model where there is failure of coordination between producers of differentgoods, and Kremer (1993) for amodel for a modelofmatchingbetweendifferent types oftalents.
"Thereis, ofcourse, a longtraditionhere,going backto
Adam
Smith. Krueger (1974) and Bhagwati (1982), amongothers, study the distortions in the allocation of talent and resources thatcomefromgovernment policies.*See Besleyand Case (1994) and Munshi (2000). Banerjee (1992) provides theoretical arguments forwhy such behaviormay berational for individual farmers.
There is along and controversial literature on this point. Thefamous Lewis model (Lewis, 1954) argued that family norms could discourage people from seeking outside options. The rational peasant model (Schultz, 1964) was articulated as a critique of
modelslike theLewismodel (see also Cole,Mailathand Postlewaite, 1992, and Banerjee andNewman,1998,fortwoverydifferentattemptsto reconcilethese views). Itis,however,
time torevisit this issue: With the increasing sophistication ofthe psychological models
used in economics, it is now possible to re-ask the question of whether, for example, poverty can havedirectdiscouragement effects.
2
Contract
Theory
in
Development
Economics
Contract theoretic arguments in development economics go back at least to the
work
of D. GaleJohnson
in the 1940'sand
1950's in the context of landmarkets/
Stiglitz's 1974 paperon
sharecropping,among
others, started a tradition of formal contract theoreticmodels
that seek to explainwhy
landlordsand
tenants often settle into arrangements that are, at least apparently, less thanfirst best efficient.^Since then, similar principles have been applied to the study of all the other important markets: capital, insurance
and
human
capital.The
resultisan
enormous
literaturewhich
Icouldnoteven begin todo
justicetowithin the hmits ofthis survey. I will confine myself, therefore^ to elaboratingon
asingle
example from
themarket
forcapital,which
Ihope
willallowme
todraw
out themost
important themes,though
at several points in the textI will point out the connections with
what
is understood about the other asset markets.3
The
Credit
Market
The
facts about the creditmarket
are remarkablystark.While
neoclassical theory predicts a single price of capital atwhich
peopleboth borrow
and
lend, at any point over the last twenty years one could point to a set of peoples inworld (most recently the Japanese)
who
were earning a negative return on their savings, while another set ofpeople were borrowing at real rates of60%
or more.Indeed,
more
often than not, very large differencesbetween
borrowingand
lendingratescan be foundwithin asinglesub-economy. Banerjee(2001) reviews anumber
ofempirical studiesofindividualcredit markets in devel-oping countriesand
lists six salient features:^1. Sizeable
gap between
lending
ratesand
deposit
rateswithin
the
same
sub-economy:
'See Johnson (1950).
*See Stigltiz (1974) and Cheung (1968).
"Thereview focuseson theinformal sectorbecausethe formalbankingsector inmost developing countries has tended to be quite rigid (interest rate caps, strict rules about
collateral, inflexiblecredit hmits,etc. [seeGhate, 1992]) with theresultthatthe informal
sector became the supplier of the marginal units of capital for all but thevery largest firms.
Ghatak
(1976) reports dataon
interest rates paid by cultivators in Indiafrom
the All India Rural Credit Survey for the 1951-2 to 1961-2 period:The
average rate variesbetween
amaximum
of18%
(in 1959-60)and
aminimum
of about15%
(in 1961-62).These
numbers
are, however, slightly misleading:around
25%
of the borrowing reported in these surveys werezero-interest loans, usuallyfrom
familymembers
or friends.These
should be seen as gifts/insurance rather than loans. If these were left out, the average rates in these surveyswould
beabove
20%.
We
are not toldwhat
thecomparable
ratesfordepositorswere
in thisperiod, butGhatak
reports that thebond
ratein thisperiodwas around
3%
and
thebank
deposit ratewas
probablyabout
the same.Timberg and
Aiyar (1984) report dataon
indigenous style bankersin India, based
on
surveys that they carried out.They
report thegap between
the average rate charged to borrowersand
the average rate to depositorsby
FinanceCompanies was
16.5%.The same
gap
for financiersfrom
the Shikarpuricommunity
was
16.5%,
12%
for financiersfrom
the Gujeraticommunity, 15.5%
for the Chettiars,
11.5%
for theRastogis, etc.The
"Summary
Report
on
Informal CreditMarkets
in India" (Das-gupta, 1989) reports resultsfrom
anumber
ofcase studies that werecommissioned by
the AsianDevelopment
Bank
and
carried out under the aegis of the National Institute ofPubhc
Finance
and
Policy. For the rural sector, the data is basedon
surveys of 6 villages in Keralaand Tamil Nadu,
carried by the Centre forDevelopment
Studies.The
average interest rate chargedby
professionalmoney-lenders
(who
provide45.61%
ofthe credit) in thesesurveys isabout52%.
While
theaveragedeposit rate isnot reported, themaximum
from aU
the case studies is24%
and
themaximum
in four out of the eight case studies isno
more
than
14%. For the
urban
sector, the data is basedon
various casesurveys ofspecific classes of informal lenders: For Finance Cor-porationstheyreport thatthe
maximum
deposit rate forloans of less than a year is12%
while theminimum
lending rate is48%.
For hire-purchase
companies
in Delhi, the deposit ratewas
14%
and
the lending ratewas
at least28%.
For auto-financiersinNa-makkal, the
gap between
the deposit rateand
the lending ratewas
19%.^*^ Forhandloom
financiers in Bangaloreand
Karur, This number and all other information about this gap is measured in percentagethe
gap
between the deposit rateand
the lowest lendingratewas
26%."
Aleem
(1990) reportsdatafrom
a studyofprofessionalmoneylenders
that he carried out in a semi-urban setting in Pakistan in 1980-1981.
The
averageinterestratecharged bythese lendersis78.5%.The
bank
rate in that year in Pakistanwas
10%. However, it ispossiblethat depositorsin thisarea
may
not havebeen
depositing inthebanks,soan alternativemeasure
ofthegap can be obtainedby
using the Aleem'snumbers
for theopportunity cost of capital to these money-lenders,which
is 32.5%.^"2.
Extreme
variability inthe
interest ratecharged
by
lenders
for superficially similarloan transactions
within the
same
econ-omy:
Timberg and
Aiyar (1984) report that the rates for Shikarpurifi-nanciers varied between
21%
and
37%
on
loans tomembers
oflo-cal Shikarpuri associations
and between
21%
and
120%
on loans tonon-members (25%
ofthe loans were tonon-members and
an-other50%
were loans through brokers).On
the other hand, the Gujerati bankers charged rates ofno
more
than 18%. Moreover, the rates faced by establishedcommodity
traders in theCalcuttaand
Bombay
markets were never above18%
and
could be as low as9%.
The "Summary
Reporton
Informal Credit Markets in India" (Das-gupta, 1989) reports that Finance Corporations offer advances for a year or less at ratesbetween
48%
per yearand
the utterly astronomicalrate of5%
per day.The
rateson
loans ofmore
than
a year varied
between
24%
and 48%.
Hire-purchasecontracts of-fer rates between28%
to41%
per year.Handloom
Financiers charge ratesbetween
44%
and 68%.
Yet the Shroffs ofWestern
India offer loans at less than
21%
and
ChitFund
members
canborrow
at lessthan25%.
points.
"A
number ofother lending instituions are also mentioned in this study. However, the range ofboth deposit rates and lending rates is so wide in these cases that the gap betweentheminimum lendingrateand themaximum
deposit rateisnotvery large. This does notrule out thepossibilitythat thegap between the average borowing and lending rateis quite substantialeven in thesecases.'^This, however, understates the gap, since themoney-lenders themselves borrow this
The
same
report tells us thatamong
rural lenders, the averagerate for professional money-lenders(who
in thissample
giveabout
75%
of thecommercial
informal loans)was
51.86%, whereas the rates for the agricultural money-lenders (farmerswho
also lendmoney)
who
supply the restwas
29.45%.Within
thecategory of professional money-lenders, about halfthe loans were at rates of60%
ormore
but another40%
or sohad
ratesbelow
36%.
The
study byAleem
(1990) reports that thestandarddeviation oftheinterest rate
was 38.14% compared
toan
average lending rate of 78.5%. In otherwords, aninterest rateof2%
and an
interestrate of150%
areboth
within two standard deviations ofthemean.
Swaminathan
(1991) reportson
asurveyoftwo
villages inSouth
Indiathat she carried out:
The
average rate of interest in one village variedbetween 14.8%
forloanscollateralizedby immovable
assets (land, etc.)and
60%
for loans backed bymoveable
assets.The
corresponding rates in the other villagewere
21%
and
70.6%.
Even
among
loans collateralized by thesame
asset—
gold—
the average rate in one villagewas 21.8%
but itwent
up
to58.8%
when
the loans were to landless laborers.Ghate
(1992) reportson
anumber
ofcase studiesfrom
all over Asia:The
case studyfrom
Thailand found that interest rateswere
2-3%
permonth
in the Central Plain but5-7%
in the northand
north-east (note that 5
and
7 are very different).Gill
and
Singh (1997) report on a survey of 6Punjab
villages they carried out.The
mean
interest rate for loansup
toRs
10,000 is35.81%
forlandowning
households in their sample, but80.57%
for landless laborers.
Fafchamps' (2000) study ofinformal trade credit in
Kenya
and
Zim-babwe
reportsan
averagemonthly
interest rate of2.5%
(corre-spondingtoannualized rateof34%)
but alsonotes that thisis the rateforthedominant
tradinggroup (Indiansin Kenya, whitesinZimbabwe).
Blackspay
5%
permonth
inboth
places.^^Irfan etal. (1999),
mentioned
above, report thatinterestratescharged by professional money-lenders varybetween
48%
and 120%.
3.
Low
levelsof
default:Fafchampsnotesthat whenhecontrolsforthe sector of theeconomy,etc., this
differ-ence goesawaybut that justtells us that thesourceof the variation issectorratherthan
Timberg and
Aiyar (1984) report that average default losses for the informal lenders they studied rangesbetween 0.5% and 1.5%
of workingfunds.The
"Summary
Report
on
Informal CreditMarkets
in India" (Das-gupta, 1989) attempts todecompose
the observed interest rates into their various components/"*and
finds that the default costs explain 14 per cent (not 14 percentage points!) of the total in-terest costs for the Shroffs, around7%
for auto-financiers inNa-makkal
and
handloom
financiers in Bangaloreand
Karur,4%
forFinance
Companies,
3%
for hire-purchasecompanies
and
essen-tially nothing for the Nidhis.The
same
study reportsthat in four case studies ofmoney-lendersin rural India they found default rates explained about23%
of the observed interest rate.The
study byAleem
gives default rates for each individual lender.The
median
defaultrate isbetween
1.5and
2%
and
themaximum
is 10%.
Production
and
trade finance
arethe
main
reasons given
forborrowing,
even
incases
where
the
rate of interest is rela-tively high:Ghatak
(1976) concludeson
the basis of his study that "the existing belief about the unproductive use of loansby
Indian cultivators... has not been substantiated."
Timberg and
Aiyar (1984) report that for Shikarpuri bankers(who
charge
31.5% on
average,and
asmuch
as120%
on
occasion), at least75%
ofthemoney
goes to finance trade and, tolesserextent, industry.The "Summary
Report
on
Informal CreditMarkets
in India" (Das-gupta, 1989), reportsthatseveral ofthe categoriesoflenders that have been already mentioned, such as hire-purchase financiers (interest ratesbetween 28%-41%),
handloom
financiers (44%-68%), Shroffs(18%-21%) and
Finance Corporations(24%-48%
for longer
term
loansand
more
than48%
on
loans of less than a year) focus almost exclusivelyon
financing tradeand
industry,and
even for ChitFunds and
Nidhis,which do
financeconsump-tion, trade
and
industry dominate.Swaminathan
(1991) reports that in thetwo
villages she surveys, the share ofproduction loans in the portfoliooflenders is48.5% and
62.8%.
The
higher share ofproduction loans is in Gokalipuram,which
has the higher interest rates (above36%
for all except the richestgroup
of borrowers).
Ghate
(1992) alsoconcludes that the bulk of informal credit goes to financetradeand
production.Murshid
(1992) studiesDhaner Upore
loans inBangladesh
(you getsome
amount
in ricenow
and
repaysome amount
in rice later)and
argues thatmost
loans in hissample
are production loans despitethefactthat theinterest rateis40%
for a 3-5month
loan period.Gill
and
Singh (1997) report that thebulk (63.03%)ofborrowing from theinformal sectorgoesto finance production. This proportion islower for the landless laborers but it is
an
non-negligible fraction (36%).5.
Richer people
borrow
more
and pay
lower
rates of interest.Ghatak
(1976) correlates asset category with borrowing/debt in the All India Rural Credit Survey dataand
finds a strong positive relationship.Timberg and
Aiyar (1984) report thatsome
of the Shikarpuriand
Rastogi lendersset acredit limit that is proportional to the
bor-rower's net worth: Several lenders said that they
would
lendno
more
than25%
ofthe borrower's net worth,though
another said hewould
lendup
to33%.
The
"Summary
Report
on
Informal CreditMarkets
in India" (Das-gupta, 1989) tells us that in their rural sample, landless laborers paidmuch
higher rates (rangingfrom 28-125%)
than cultivators(who
paidbetween
21and
40%). Moreover, Table 15.9 in that report clearlyshows
that the average interest rate declines with loan size (from amaximum
of44%
to aminimum
of 24%).The
relation
between
asset categoryand
interest ratepaid islessclear in theirdata
but it remains thatthesecond poorestgroup
(those withassets intherangeRs
5,000-10,000) pays the highestaverage rate(120%) and
the richest (those withmore
thanRs
100,000)Swaminathan
(1991) finds a strong negative relation between the value ofthe borrower's land assetsand
the interest ratehe faces:The
poorest (those with no land assets) pay44.9%
inone villageand
45.4%
in theother, while the rich (thosewith land valued atmore
thanRs
50,000) pay16.9% and 24.2%
in thecorrespondingvillages.
Gill
and
Singh (1997)show
that correlationbetween
thewealthofthe borrowerand
loansizeisnegative aftercontrollingfortheinterest rate.They
also find a positive relation between the borrower's wealthand
the loan he gets.6.
Bigger
loansare associated
with
higher
interest rates.Table 15.9 in the
"Summary
Report on Informal CreditMarkets
in India" (Dasgupta, 1989) clearlyshows
that the average interest rate declines with loan size (from amaximum
of44%
to amini-mum
of24%).Ghate
(1992) notes that the interest rateon
very small loans inBangladesh
tends to bevery high (Taka 10 perweek on
a loan ofTaka
500, or86%
perannum).
Gill
and
Singh (1997)show
that the correlationbetweenloansizeand
theinterest rateisnegative evenafter theycontrolfor thewealth ofthe borrower.
3.1
Tciking
Stock:
The
Facts
about
Credit
Markets
The
fact that there is agap
between the lending rateand
the rate paid to depositors is not, per se, surprising.The
fact that intermediation is costlyis, after all, entirely
commonplace.
What
is striking is the size of the gap. It is alwaysmore
than10%
and
usuallymore
than 14%, in a worldwhere
interest ratespaid to depositors arerarely
more
than
20%
and
usually closer to 10%. Inother words, intermediation costsseem
to eatup
at least a thirdand
often half (and sometimesmuch more
than half) of theincome
that could go to depositors.However, this
argument
overstates the point slightly.The
probabihty that amoneylender would
default on his deposit liabilities is substantially lower than the probability that borrowers will defaulton
the loan,which
implies that the defaultpremium
on
loansshouldbemuch
greater than the defaultpremium
on
deposits.From
the evidence reported above, default is10%.
The
gap between
loanratesand
deposit rateswould
bevery large evenif
we
wereto deduct10%
from the loan rate.'^^^The
fact that interest rates vary quite somuch
is particularly striking given the standard neoclassical prediction that inmarket
equilibrium the marginalunit ofcapital inevery firmshould earn thesame
return. However, given thatpeoplemight
be rationed in the credit market, it is theoretically possible that the marginal product of capital is actually equal in all itsuses, despite the
enormous
disparities in the interest rate.Note
that the incremental capital/output ratio for the Indianeconomy
is estimated to bearound
4.3, implyingan
marginal returnon
capital of24%.
This is,however, a gross
measure
and
the truereturn, net of depreciation, isclearly substantially lower (nomore
than 20%).The
fact that interest rates above35%
are standard,and
those above75%
are byno
means
rare, suggests that at leastsome
ofthe users ofcapitalmust
valuecapital at substantiallymore
than 20%.
Could
it bethat allofthedemand
at relativelyhighinterest ratescomes
from
peoplewho
haveparticularly insistentconsumption
needstoday? Thisis certainly not the stated purposeof the loans, as noted above.
Of
course,money
is fungibleand
one cannot ruleout the possibilitythatsome
ofthese people are either deluded or untruthful. However, it remains thatwhen
a hajidloom producer borrows at48%
ormore
to finance consumption, he chose todo
so instead of taking themoney
out of his existing business. Therefore, itmust
be that hewould
losemore
than
48%
on
anymoney
thatcomes
out of his business. Thismay
be
in part because in the short run his assets are not liquid, but this could not explainwhy
heaccepts ongoing financingon
these terms. Therefore, hemust
be earning marginal returns that are close to 48%.^'^Onemightbeworriedthatwhile default rates arelowon average, default
may
bevery importantin those cases wheretheinterest rate ishigh. However, this isnot aproblemsince, for themost part, welook at interest ratesand default rates weighted by volume
(or equivalently, do a Bottomley [1975) decomposition). Moreover, in the one detailed micro-study wehave where the average interest rate is very high (Aleem, 1990), default ratesare actuallyvery low (alwayslessthan10%, and usuallylessthan 2%).
'^Delay
in repaymentforwhich noextrainterestischarged isanotherfactorthatreiises
the interest rate. In Aleem's data, delay is much more
common
than default, but in asignificant fraction of the cases the lender is able tocharge interest for the extra days.
Moreover, thepercentageofloans that arelatenever exceeds 25% and theaverage delay
isnomorethan6months, soatworstthiswouldraisetheinterestratebya factor of1.12.
There is,onceagain, the possibihty that a part ofthe reasonwhy these rates are so high isbecauseofdefaultrisk. Inotherwords,theexpected returnon themarginalunits of capital need not be ashigh as48%. However as already observed, defaults contribute
The
factthat the marginal product of capital varies substantially across borrowers in thesame sub-economy
is supportedby
more
direct evidencefrom
the knittedgarment
industry basedon
data that I collected in jointwork
withKaivan
Munshi
(Banerjeeand
Munshi, 2001). Tirupur produces70%
of India's knittedgarment
exports,and
India is amajor
exporter of knitted garments.There
aretwo
communities of producers in Tirupur: Gounders,who
are linked bycommunity
ties to a rich local agriculturalcommunity;
and
Outsiders, a motley crew of businessmenfrom
all over India.They
produceexactly thesame
goods, yet they useradically different technologies.Gounders
investmuch
more
than Outsiders at all levels of experience, both in absolute termsand
relative to output.Average
capital-outputratiosforGounders
can bethreetimes as large as that for Outsidersand
is typically twice as large. However, all the evidence points to the Outsidersbeingmore
able: theyenjoyfasteroutput growthand
theiroutput outstrips that of theGounders
after a few years.One
possible situationwhere
high ability peoplemay
invest lesswould
be ifcapitalwere lessusefulfor them,
which
would
be the caseifabihtyand
capitalweresubstitutes in the productionfunction.
The
evidence, however, points againstthisexplanation:When
we
compare Gounders
withGounders
or Outsiders with Outsiders, it is clear that those
who
grow
fasterand
produce more
also invest more. Therefore, it seems relatively clear that the Outsiders invest less despite having a higher marginal product ofcapital.What
explainswhy
the credit markets behave in thisway?
Why
isintermediation soinefficient with
some
peopleand
so efficient withothers?Why
are the rich borrowersand
thosewho
borrow
more
favoredby
themarket?
The
standardtheory ofinterestratesdecomposes
them
intodefaultrates, opportunity cost, transaction costsand
monopoly
rents. This is useful de-scriptivelybutstops well short ofan explanation—
theproblem
is thatnone
of these can be seen as independent causal factors.
Take
theexample
of default rates.The
fact that default rates are relatively low is not a fact about the nature of default:Timberg and
Aiyar (1984) observe thatsome
'*ThisiswhatCaballeroandHamraour(2000)callscrambling. Theproximatereason,itappears,istheGoundershavealotof investiblefundsthatthey cannotprofitablylendout becauseintermediation is soinefficient inIndia. Instead, theysetup their owngarment firms orlend to friendsand family inthe garment business. Since these firms areset up asa conduit for thissurplus capital, they are not required tobeparticularly productive.
The Outsiders, by contrast, come from traditional entrepreneurial communities and, as
a result, their capital probably has many alternative uses. In other words, they do not
invest in Tirupur because they lack other choices. This makes them more likely to be productivebut alsolesswilling to investalot.
branches of the state-owned
commercial
banks
in India have default ratesup
to 60-70%.The
lowdefault ratesobserved in the studieswe
mention
are a result ofthe steps takenby
lenders to avoid default.Monitoringthe borrower is
an
obviousexample
ofthekindof steps that lenders take. It is alsoan
important source ofwhat
goies under the rubric oftransaction costs:Aleem
(1990)and
Irfan et al. (1999) provide a list of steps takenby
the lender to avoid default.These
include getting toknow
theborrowerthrough other transactions, visiting his establishment,
making
enquiries about
him
and
going afterhim
tomake
sure he repays.Lenders also protect themselves
by
limiting their lending to borrowers they know.^^ This has fourimportant consequences. First, itpushescapital towards well-connected borrowersand away
from less well-connected bor-rowers, evenwhen
there isno
difference in their productivity. Second, itmakes
it important that lending be local—
the lendermust
know
and
trust hisborrowers. This addsone ormore
layers ofintermediation to the process of lending, with additional transaction costs entering at each of the stages,which
raises the opportunity cost ofcapital. Third, it forces the lender to limit his lending, with the consequence that both his capitaland
his skills as a lendermay
remain
unused
for asignificant part ofthetime. This raisesboth
the opportunity cost of the capitaland
the transaction cost (which includes a part of the lender's time). Finally, it gives the lendersome
ex postmonopoly
power, as a borrowerwould
find ithard
to leave a lenderwho
knows
him
well.Under
competitive conditions, these ex post rentswill be dissipated in ex ante competition, with lenders in effect subsidizingnew
borrowers in order to extract rents later
from
thosewho
willbecome
his long-term clients.What
thistellsus isthat the fourcomponents
ofthe interest rate are alljointlydetermined in the process of the lender
making
his lendingdecisions.Depending on
the lender's strategy, it could be that the transaction costsdominate
or the opportunity cost dominates or that default ormonopoly
rents
become
very important.The
strategy could be very different depend-ingon
the nature of the clienteleand
other environmental characteristics. Thismay
be a part ofthereasonwhy
different people have taken very dif-ferent views ofinformal credit markets: Aleem, for example, finds that for every rupee lent, about half a rupee goes into transaction costs, while inDasgupta
(1989) onlyabout
30%
of interest costs are explainedby
trans-action costs (strictly establishment costs) whileGhate
(1992) argues thattransactioncosts are
unimportant
except in the case of very small loans.^^The
fact that allthese decisions areinterrelated clearlymakes
itdanger-oustouseanysingleoneof these
components
asameasure
oftheefficiency of intermediation. For example,Ghate
(1992) sees thelow levelof transaction costs inhissampleasevidencefortheremarkable efficiencyofinformal lend-ing. But, as has alreadybeen
noted, transaction costsmay
be low because the lenders are very choosy about towhom
they lend. This raises the op-portunitycostofcapital (since capitalis often idle)and
limits credit access,both
ofwhich have theirwelfare costs. Likewise, the low rate of defaults in informal transaction is oftenmentioned
as evidence for their efficiency, but this is obviously misleading if itcomes
at the cost of increased monitoring or reduced lending. Finally, the presence ofrents in lending is not, per se,evidence for lack of competition in the market.
As
pointed out above, in this type ofmarket, ex post rents are consistent with ex ante competition.A
further implication of this observation is that both loan sizeand
the interest rate are jointly determinedand
therefore one cannot give a causal interpretation of the relationbetween
interest ratesand
loan size reported above. Rather, one should seeboth
of these asoutcomes
that aredeter-mined
bymore
primitive variables such as the wealth of the borrower, his productivity, the liquidity of his assets, etc. This alsomakes
it harder to interpret the reported negative relation between the borrower'swealthand
the interest rate. In principle, it could be entirely a result of the fact that rich borrowers
borrow
more.Most
importantly, this line ofargument
underscores the importance of developing a proper theory of credit markets.Such
a theorywould
explain the variationininterestratesand
thegap
betweeninterest ratesand
deposit rates in terms of the true primitives of the model,and
make
predictions about the relationbetween
loan sizeand
interest ratesand
borrowerand
lendercharacteristics.
While
thereis a long tradition ofmodels
ofimperfect creditmarkets going backtoJafFeeand
Russel (1976)and
Stiglitzand
Weiss (1981),and
thearguments
behindwhy
credit markets can fail, basedon
moral
hazard and/or adverseselection, arewell-known, Ifeelthat itisuseful todevelop aframework
that has amore
direct empirical orientation.^"Evenwithin thesetof case-studiesreportedby Ghate,thereseems tobeconsiderable
variation. In Kerala, the case-study concludes that transaction costs are of negligible
importancewhile theThaistudy concludesthat transaction costsadded between3 andl4 percentagepoints to theinterest cost.
3.2
A
Simple
Model
of
Moral
Hazard
inthe
Credit
Market
There
isan
investmentopportunitywhose
gross returns areF{K)R{p)
withprobabihty
p and
otherwise,where
K
is theamount
investedand
F{-) isa production function. If
an
investor wants to investmore
than
his wealth,W,
hewill needtoborrow.There
is a capitalmarket
and
the (gross) cost of capital in thatmarket
is p.To
make
thisproblem
interesting it isassumed
that:
1
.
p
is a choicefor the investor but is unobservedby
the lender,p
takes a valuebetween
poand
p\.
2. E{p)
=
pR{p)
has theproperty that E'{po)>
0,and
E"{p)<
0.3.
The
only possible contract is a loan contract.^'3.2.1
The
Basic
Moral Hazard
Problem
The
optimal value ofp, p* is clearly greater than poand
may
ormay
not be less thanpi.The
combination oftherest oftheassumptions tell us thatthere is
no
guarantee that p*would
be chosen in equilibrium.To
see this,note that the borrower,
who
isassumed
to be risk-neutral, will choosep
tomaximize
F{K)E{p)
—
pr{K —
W)^
where
r is the interest rate that has to be paid to the lender tomake
him
wiUing to lend.The
borrower will choosep
such thatE'[p)F{K)
— r{K
—
W) =
0.^^This is quite obviously inconsistent withthe social
optimum:
the borrower clearly wants to choosep
<
p* This is the standard incentiveproblem
in credit markets: Society cares about net output but theborrower only cares aboutwhat
remains after paying interest. This is the essence ofallmodels
of ex ante moral hazard in thecredit market.
Next, notice that the first order condition for the borrower's choice of
p
can be rewritten in the form:^W^=r(l-f).
(I)Prom
this equation it is evident thatp depends on
three things:The
average product of capital,
F{K)/K;
the leverage ratioK/W;
and
the in-terest rate, r. Ifcapital ismore
productive, the borrower is less inclined to 'This rules out making the borrower's payments depend on the project's reahzedre-turns. Diamond (1989) justifies this assumptionby assuming that the recJized return is
notpubhcly observable except by makinguse of a liquidation proceeding, which iscostly to the point ofusing up all available output. This makes sure that a borrower will not
willfullydefaultaslongasthe lender threatens togointoUquidationwheneverhedefaults.
misbehave,
and
thisis reflected in a lower p. Beingmore
leveragedworsens hisincentivesand
sodoes a higherinterest rate,which
is consistent with the observationmade
above that the interest costburden
is the source ofthe distortion.Property
1. Efficiency:There
is less inefficiency inthe
credit relationship
when
there
is less leveraging,when
the
interest rate is lower,and
when
the project
ismore
productive.
From
this it followsthat the equilibrium value ofp
can be writtenin the form:p
=
piR,F{K)/K)-,
where
i?=
r(l— ^)
is the interest cost per unit of investment. Clearly^
<
and
Qpix)IK^
^- Writing the relation in this formdraws
attention tothe important roleplayedby the shapeoftheproduction function.When
F{-) isconcave,F{K)/K
decreasesasa function ofK.
Therefore,thosewho
invest
more
willbe more
liable to moral hazard, even after controlling for the leverageratio. However, ifF
is convex, at least over a range, increasing thelevelofinvestmentmay
increaseprofitabilityand
improvethe borrower's incentives.As we
will see, this distinctionmay
be very important forsome
questions.3.2.2
The
InterestRate
We
have so far treated r as a parameter. In fact, if there is competition in lending, lenders should notmake
any profits,which would
imply thatr
=
p/p, (2)or
R
= p{l-W/K)/p=-,
P
where
F
isthe cost ofcapitalper unit of investment.^^ Solving^=
p{R,F{K)/K)
along with
R
=
T/p, gives usp
=
p{T,F{K)/K)
and
R
=
R{T,F{K)/K).
^^The assumption ofperfect competition in the credit market is not uncontroversial.
Thereisalongtradition ofpapersthatview highinterestratesasevidenceformonopoly power in the credit market. However,as already pointed out, the issue of rents in the creditmarketislikelytobequitedelicate,sincecompetitionoperates ex ante ratherthan
expost. Therefore, theabsenceof ex ante rentsisconsistentwith Bhaduri's (1977) model
However, it is easy to construct
examples where
these equations have mul-tiple solutions: Intuitively, a fall inp
raises r, but arise in r, aswe
already saw, putsdownward
pressureon
p. It is not clear, however, thatwe
can interpreted theseas multipleequihbria—
ifthe lenderknows
the rules ofthe game, heknows
that he can pick the best equilibriumand
make
everyone better off, simply by setting the right interest rate. Therefore, unless the lender isboundedly
rational,we
shouldprobablyassume
thatthe best equi-librium is always chosen. This is the equilibrium with the lowest interest rate.Assuming
thatthisistheequilibrium, thecomparativestatics ofthep(-) function are inheritedby
the p(-) function,and
r=
& shares the properties ofthep
function, onlyreversed.A
lower leverageratioincreasesp and
lowers the interest rate, as does a higher average product ofcapital.Lowering
the cost ofcapital lowers the rate of interestmore
than proportionately since therepayment
rate goes up.Property
2. InterestRates:
Borrow^ers
who
are
more
leveraged
tend
topay
higher
rates,while
more
produc-tive
borrowers
pay
lower
rates.Raising the
cost of cap>-ital raisesthe
interestrate
more
thEinproportionately.
3.2.3
The
Level
ofInvestment
The
next stepistoendogenizethelevelofborrowing.The
borrower's choice ofK
maximizes
F{K)E{p)
-
p{K -
W)
under
the assumption thatp
depends
on
K
through the p{-) function.The
first order condition for that
maximization
is:If
we
compare
this with the first order condition in a first best world,F'{K)E{p*)
=
p,we
see that there are three sources of distortion. First,E{p)
<
E{p*),which
says that capital is less productiveand
therefore the borrower wants to investless. Second,^
is negativewhich
alsodiscourages evidenceseemsto supportthehypothesisof exantecompetition: Thefewstudies(Ghate (1992), Dasgupta (1989), Aleem (1989) that compute the gap between the interest rate chargedandthe various costsoflending(opportunitycost, monitoringcosts,defaultcosts)donot find alargegap on average, though one cannot rejectthe possibihty that there is
investment. Finally,thereisthesecond
term
ontheleft-hand-side,which
can be positive or negativedependingon
the sign of—
qk~-
This, aswe
have already observed,depends
on whether
the production function is concaveor not. Ifit isconcave, the second
term
isnegativeand
it isunambiguously
true thatimperfections inthe capital
market
lead tolessinvestment. Ifnot, the secondterm
may
be positiveand
ifthis effect is large enough, it could outweigh the first effectand
generate over-investment.Whether
this possi-bility is actuallyworth
taking seriouslyremainsan
open
question, awaitingmore
precise calibrations of the model.^'*Another
important propertyofthe first best isthattheamount
investedisindependentof thewealthoftheinvestor. Inourpresent model, if
we
wereto increase
W,
keepingK
fixed,we
know
from
Property 1 thatp
would
go up, raisingE{p)and
reducing E'{p).As
long asF
is concave,both
ofthese effects go in thesame
direction:They
both
raise the rewards for investing more,and
therefore there ismore
investment.^^ Infact, in the special casewhere
F{K)
=
aK,
i.e., a linearproductiontechnology,K
not only goesup
when
W
goes up, it is precisely proportional toW.
The
general case ofa non-concaveF
tends to be complex.One
inter-esting example,where
there is a single indivisible investment, turns out to be very straightforward. In this case people either invest ordo
not,and
since those
who
havemore
wealth choose a higherp
at thesame
level of investment (Property 1), they are the oneswho
will invest.More
generally,non-convex production technologies raise the possibility that the poor vdll actuallyinvest
more
than the rich: Intuitively, ifthe production function isconvex, increasinginvestment raisesproductivity,
which
improvesincentives through its direct effect. However, there is alsoan indirect effect: Investingmore makes
the borrowermore
leveragedand
this worsens incentives.The
balanceofthese
two
effectsmay
be
different for therichand
the poor, since their incentive problems are different,and
in principle it could be that thepoor
end up
investing more. However, it seems unlikely that these effectswould dominate
themain
effect of being richer, whichis that (at thesame
levelof investment)richerpeople arelessleveraged
and
thereforehavebetter incentivesand
as a result their capital ismore
productive.Loweringthecost ofcapital in this
model
increasesp and
this, as argued above, encourages investment. However, lowering the cost of capital also increases theamount
invested in the first best, so that there isno
clear^''Lehnert, Ligonand Townsend (1999) argue that this isareal possibihty.
^^Actually, there is a third effect: Increasing
W/K,
it can be shown, reducesprediction for the extent ofunderinvestment.
Property
3.The
Level
ofInvestment:
Capital
market
imperfections lead to
under-investment
inthe
typical case,though
it isnot inconceivable that
they
could
gen-erate over-investment.
The more
wealthy
willtend
to
invest
more
inabsolute terms.
When
the
production
technology
is linear,the
amount
invested
willbe
propor-tional to
the
investor'swealth.
When
there
isa
single indivisibleinvestment,
the
richare
more
likelyto
investthan
the poor.
Lowering
the
cost of capital increasesinvestment.
Capital
market
imperfectionsreducethedemand
for capital. Fora given supply curveof capital, thismeans
thatthecostofcapital willbe
lowerthanit
would
be otherwise. In the longer run, however, the supply of capital will alsorespond to thepattern ofwealth creation generatedby
the capitalmarket
imperfectionand
the net impact onthe cost of capitalis ambiguous.Property
4:The
Cost
of
Capital:For
a
given
supply
curve
for capital,imperfect
capitalmarkets
willhave
a
lower
costof
capital,but
this isno
longer
necessarilytrue
once
we
take
intoaccount
the
impact
of
the
capitalmarket
imperfection
on
the
supply
of
credit.3.2.4
Introducing
Monitoring
The
model
developed so far is usefulin developing intuitionabout
how
the creditmarket works
butithasan
importantlimitationin termsofexplaining the data.As
we
have already seen, therepayment
rates inmost
informal credit transactions arevery high (over90%). It followsfrom
equation 2that the interest chargedby
a competitive lender can onlybe
about10%
higherthan
the cost ofcapital,which from
alltheevidenceabove
ismuch
too smalla
margin.The
missing piece of the story is monitoring.We
haveassumed
so far that the lender cannotdo
anythingto affectthe borrower's choice ofp. Thisis clearly
an
extreme assumption, since, as already mentioned, lenders canand do
monitorborrowers.The
point of all these activities is to learnmore about
the borrower. Thishelps intwo
ways: First,by
allowing the lenders to pick borrowers forofmoralhazard.
And
secondby gettingtoknow
the borrower'senvironment, therebymaking
it easier to find outwhen
the borrower is not doingwhat
he has promised to
do
with the money.In addition to this kind of ex ante monitoringthereis ex post monitoring ofthe project, checking that the borrower has
done
what
hehad
promised todo
with the money. For example, the lender can try tomake
sure that the borrower is spending themoney
on inputs for his project ratheron
consumption. Finally there is collection:
Once
the loan fallsdue, the lender has tospend time chasing each overdue loan.It is not possible to capture all of these different aspects ofmonitoring in a single model, so
we
limit ourselves to one specific model,though
some
ofthe othermodelswill
be
discussed in a later section.We
introducemon-itoring into the
model by
assuming that ifthe lender monitors at a level a, the borrower will chose a project p(o) or a project with ap no
lower than p(a).^^We
assume
that thiscomes
about either through ex ante monitor-ing ofthe project (screening of projects before the loan is given) or ex post monitoring ofthe project (checking on theborrower after he has been given the loanand
punishinghim
ifhe has notdone
what
hewas
supposed to do).The
problem
is thatwe
know
very little about the nature of the empirical relationbetween monitoringand
project choice.The
only optionwe
have isto reason on purely a priori grounds.
One
assumptionthathasa certainplausibilityisthattheamount
ofmon-itoring necessary is a function of the extent of
misahgnment
of incentivesbetween
the borrowerand
the lender.The
borrower in ourmodel wants
tochoosep
=
p{R,F{K)/K),
whichgiveshimapayoSoi
F(K)E{p{R,F{K)/K))-p{K
/W,r,F{K)
/K)r{K
—
W)
, while the lenderwantshim
tochoosep
whichgives
him
a payoff ofF{K)E{p)
—
pr{K
—
W).
The
extent ofmisahgnment
istherefore
D
=
F{K)[E{p{R,
F{K)/K))
-
Eip)]-
\p{R,F{K)/K) -
p]RK.
(4)Our
assumption is then that theamount
of monitoring is a function of D. However, inorder to allow for different types ofscale effects,we
write it in a slightlymore
general form:M
=
M(A',D//\",m),where
m
is a parameter that shifts the monitoring cost function(^
>
0). "*Theborrower willtypicallychoose the lowest permissible value.3.2.5
The
Cost
ofCapital
with
Monitoring
The
lender's participation constraint (2)now
takes the form:^^T_^MiK,D/K,m)_
^^^
p
Kp
This equation defines
R{r,K,p,m),
the interest rate for a borrower with a fixedW
who
wants
to invest anamount
K
and
promises to choose a projectp. Using this,we
can define the expected cost ofcredit per unit of investment:C{r,K,p,m)
=
pR.
This formulation ofthe supply side of credit has the obvious advantage that the interest rate can be
much
higher than the cost of capital even ifdefaults arerare. Thisisbecause monitoringcostscan
be
very high—
indeed the reasonwhy
there is very little defaultmay
be a result of the resources spent on monitoring.It is useful to begin our analysis ofthis
model
withan
examination of the properties ofthe C(-) function. Simple differentiation tells us:dR
_
1af
~
p-p{R,F{K)/K)dM
^"""^^
K
d{D/K)dR
dM/d'
rndm
A'[jD P-P(R,F(K)/K)K
d{D/K)idM
Since [p—
^""^' '^'—
^
—
afo/K)!
^
P^ ^^^^ *®^^ ^^ *^^^ increases in the costof lending (represented
by
a rise inp
or in rn) have a multiplier eflFect,resulting in a bigger increase in the interest rate than
would
be warrantedby
thedirect effect ofthe increase in cost.^' This is because the initial rise inthe interestrateworsensthe borrower's incentivesand makes
it necessary that he be monitored more,which
raises the cost of lending even further, etc. This property is obviously also inheritedby
theC
{) function.Property
5. Multiplier:The
interestrate
and
the
amount
ofmonitoring can
be
very
sensitiveto
changes
inthe
costof
capitaland/or
the
costof
monitoring.
This is an important property: It tells us that there are even relatively small differences in themonitoring cost, or the cost ofcapitcd can induce a
lot of variation in the interest rate,
which
helps to explainwhy we
observe somuch
variation.^''in principle, this increase can be very large since [1
-
P ''^^'^^''^^^^^g-p^^.J can bevery close to oreven negative (in which case, the equilibrium interest changes
A
relatedand
important property oftheC
{) functioncomes
from dif-ferentiating equation5 with respect top. This, aftersome
algebraic manip-ulations, gives us:dC _
1dM
p{R,F{K)/K)RK
-pF{K)E'{p)
~dp
~
K^d(D/K)
ip-p{R,F[K)/K))dM
•
^ ' ^ -f
K
d(D/K)Equation 1 tells us that
E'{p{R,F{K)/K))F{K)
=
RK.
Usingthis (assum-ing thatp-
J^-qMMj^{p-p{R,F{K)IK))
>
0), it is immediately clearthat the sign of^
depends on
the sign oip{R,F{K)/K)E'{p{R,F{K)/K))
-pE'{p). Since
p
>
p{R,F{K)/K)
it follows thatCp
can only be positive ifthe functionpE'{p) is a decreasing function of
p
over a range.This
makes
it clearthat it is entirelypossible thatCp
be negative forallp, implying that implementing high values of
p
may, paradoxically, require less monitoringthan
implementing lower values. This is because a highp
generates a lowR
and
this improves incentives.In such situations it
may
be optimal to raisep
all theway
to itsmaxi-mum,
i.e. topi- Inparticular, this willbe true as longasE{p) iseverywhereincreasingin
p
overits admissible range^^and
it willremaintrue irrespective ofhow
costly it is to monitor}'^ However, it is easy tosee that it willnever be optimal forp
to exceed its social welfaremaximizing
level, i.e the value ofp
forwhich
E'{p)=
0. This is becausewhen
E'{p)—
0,Cp
is clearly positive.Property
6.Default:
Very
low
levels of defaultmay
be optimal
even
when
monitoring
isquite
costly,though
it isnever optimal
to
have
less defaultthan
inthe
socialoptimum.
This is important because it tells us that it is often optimal to
aim
for very low default rates even at thecost of lots ofcostlymonitoringand
high interest rates. This is reassuring, given that the combination of very low default ratesand
very high interest rates isby
no
means
uncommon.''''3.2.6
The
Optimal
Credit
Contract with
Monitoring
The
optimal creditcontract will be a combination {K,p) that maximizesF{K)E{p)
-
pR{T,
K,
p,m)KM.
^*For example, Cp is negative whenever E(p) takes the form Ap^, with
^
> and/3e(o,i).
^'Ofcourse, thisisconditional onthe loan contractbeingviable,whichis not the case
whenmonitoringistoocostly.
The
firstorder conditions that describetheoptimal contract(when
it is nota corner solution) are
F{K)E'{p)
= KCp
and
(6)F'{K)E{p)
=
C
+ KCk.
(7)There
is, however, relatively little thatwe
can say about the optimal credit contract at this level of generality.The
problem
is easily seenfrom
equation 5:
An
increase inK
affectsboth
thenumerator
and
thedenom-inator of the expression
—
(k'-vv)p ' ^^'^ without
more
structure it is notpossible to say anything about
now more
investment affects the expected cost of lending.The Model
with
Constant
Returns
inMonitoring
One
simpleand
fruitful
way
toimpose
structure istoassmne
constant returnsin monitoring,i.e.,
M{K,D/K,m) = KM{D/K,m).
For the
most
part,we
will alsoassume
that there are constant returns in production, i.e.,F{K)
=
aK.
In this case, equation 5 canbe
rewritten in the form:pR =
T
+
M{a[E{p{R,a)
-
E{p)]-
\p{R,a)-
p]R,m).
R
istherefore a function ofa,m,
p and
F,and
so is, therefore, theexpected cost oflending C. It follows that keepingp
and
F
fixed, doubling the bor-rower's wealthand
theamount
he invests does not change the unit cost of lending. It follows that all borrowers withthesame
a
and
thesame m,
will choose thesame
leverage ratioand
face thesame
interest rate. In other words,under
full constant returns the richand
the poor willpay
thesame
rate ofinterest as long as they are equally productive.
The
rich will simply invest more.The
directprediction ofthismodel
istheabsenceofa correlationbetween
the borrower's wealth
and
the interest rate.Of
course, aswe
will see later,it does not rule out the possibility of a spurious correlation, induced
by
a correlationbetween
W
and
eithera
orm.
Nevertheless, this resultprovides a usefulbenchmark:
It tells us that there isno
necessary reasonwhy
the richshouldpay
lower interest rates, as observed in the data.The Model
with
a
Fixed Cost
ofMonitoring
A
model
thatmanages
to account for
most
ofthe observed fairly economically is onewhere
thereis a fixed cost of monitoring
which
has to be paid as long as there issome
borrowing
and
a variable cost which, as before, exhibits constant returnsi.e.,
M{K,
D/K,
m)
=
KM{D/K,
m)
+
$. In this case, equation 5 can be rewritten to readpR
=
T
+ ^/K +
M{a[E{p{R,
a)-
E{p)]-
\p{R,a)-
p]R,m). (8)With
these assumptions,we
run the risk that the lender's maximizationproblem
may
not be convex:To
see why, note thatT
+
^/K
=
p{l—
W/K) +
^/K,
which
tells us that if$ >
pW
,R
goesdown when
K
goesup, encouraging the borrower to
borrow
even more. Conversely, aborrowerwho
borrows httlewillpay
very high rates,making
it attractive forhim
to notborrow
at all, suggesting the possibility ofa "bang-bang" solution.As
long as
we make
sure thata
is not too large (to avoid the possibihty that thedemand
for creditbecomes
infinite), the solution will be for thepoor
borrower
{pW
<<<!>) toborrow
nothing.However,thereisaninteriorsolutionforborrowers
who
arericher{pW
»
$). It is easily checked that this interior solution has a very simple prop-erty:Prom
equation 8 it follows that as long as p, a, pand
m
are held fixed,R
is completely determined by theterm
{pW — ^)/K
and
thereforeC
=
C{
Pj^ ).
From
7 the optimalchoice ofK
satisfiespVF-^
pW~^
pW-^
^ <y
= c:(—
^-)
4-—
^-c
(—
^-)
in this case, which tells us that ^
^
is uniquely determinedby
a.A
number
of properties follow immediately from this observation. First, an increase inW
results in amore
than proportional increase inK:
In other words, richer people aremore
leveraged. Second, higher values of$
are associated with a lower value ofK.
Third, changes inW
and
$
do
not affect R, fromwhich
it follows that r goesdown when
W
goesup
(sinceK/W
goesup and
R
remains unchanged).There
is a straightforward intuition behind these results.Given
that thereis afixed cost of lending, thosewho
investmore
will face a lower cost ofcapital. However, fora poor person tobe able toinvest thesame
amount
as a richerperson, the leverageratio