International Monetary Theory: Mundell Fleming Redux...v International Monetary Theory: Mundell...
Transcript of International Monetary Theory: Mundell Fleming Redux...v International Monetary Theory: Mundell...
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International Monetary Theory:Mundell Fleming Redux
by
Markus K. Brunnermeier and Yuliy SannikovPrinceton and Stanford University
Princeton Initiative Princeton, Sept. 9th, 2017
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Motivation
Global currency spilloversβ’ βFlight to safetyβ - Dollar appreciation when risk rises
β’ Local currency: good store of value/hedge for idiosyncratic risk
β’ Global currency: good hedge for international competitiveness risk
When to peg to world currency? When to dollarize?
MoPo space: βNuanced Mundell-Fleming Trilemmaββ’ Local and global money have different risk profile (imperfect substitutes)
β increases MoPo space
β’ Too high inflation: local citizens substitute local currency for global currencyβ limits MoPo space
Reserve currency management β Irrelevance theorem
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Modelling Framework
Closed economy Open Economy
Static Hickβs IS-LM Mundell-Fleming
DynamicImpulse response
New Keynesian Obstfeld-Rogoff
Risk & Dynamicfinancial frictions
Samuelson BewleyDiamond Aiyagari X
I Theory of Money
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Modelling Framework
Closed economy Open Economy
Static Hickβs IS-LM Mundell-Fleming
DynamicImpulse response
New Keynesian Obstfeld-Rogoff
Risk & Dynamicfinancial frictions
Samuelson BewleyDiamond Aiyagari X
I Theory of Money
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Modelling Framework
\Friction OLG Incomplete Markets + idiosyncratic risk
Risk deterministic endowment riskborrowing constraint
investment risk
Only money Samuelson Bewley
Basic βI Theoryβ
With capital Diamond Aiyagari
πβ² πβ = πβ, Dynamic inefficiencyπ < πβ, πΎ > πΎβ
Inefficiencyπ < πβ, πΎ > πΎβ
Pecuniary externalityInefficiencyπ > πβ, πΎ < πΎβ
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Frictions
Incomplete marketsβ’ Within country
only w.r.t. idiosyncratic risk π ΰ·¨ππ‘π
(other risks can be shared within national economy)
β’ Across countries Only global money can be traded
Money is a bubble Like in Samuelson, Bewley
Price are fully flexible
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International setting
Small Economy
β’ Local currency Store of value Hedge against idiosyn-
cratic risk
β’ Consumption basket Non-tradable local good ππΎπ‘ tradable good 1 π1,π‘πΎπ‘ tradable good 2
Large Economy*
β’ Global currency* $ β¦ Hedge for SOEβs citizens against
βinternational competitive riskβ
β’ Consumption basket* Non-tradable good* πβπΎπ‘
β
tradable global good 1 π1,π‘βπΎπ‘
β
tradable global good 2 π2,π‘βπΎπ‘
β
Exchangerate
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Large Economy*
β’ Global currency* $ β¦ Hedge for SOEβs citizens against
βinternational competitive riskβ
β’ Consumption basket* Non-tradable good* πβπΎπ‘
β
tradable global good 1 π1,π‘βπΎπ‘
β
tradable global good 2 π2,π‘βπΎπ‘
β
International setting
Small Economy
β’ Local currency Store of value Hedge against idiosyn-
cratic risk
β’ Consumption basket Non-tradable local good ππΎπ‘ tradable good 1 π1,π‘πΎπ‘ tradable good 2 π2,π‘πΎπ‘ π2,π‘
π1,π‘<π2,π‘β
π1,π‘β
Exchangerate
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Intuition
Purchase good 2 in exchange of good 1 (depends on ToT)
Hold global money as Net Foreign Asset Position
Value of money β money is safe assetβ’ Local money is store of value with nice hedge against
idiosyncratic risk
β’ Global money ($) hedges better βexport riskβ (competitiveness = ToT + productivity)
β’ 2 money can coexist (even though both are βbubblesβ) Different return-risk profile
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Overview
Large countryβ’ Portfolio choice between
Physical capital ππ‘β
US Dollar, $ β βbubble in positive net supplyβ
β’ No state variable: due to scale invariance
Small countryβ’ Portfolio choice between
Physical capital ππ‘ Peso βhedge against idiosyncratic shocksβ
US Dollar, $ βhedge against ToT + export productivity shocksβ
β’ State variable ππ‘:Accumulation dynamics of foreign asset position (in $)
ππ‘π₯ = ππ₯ ππ‘ , ππ‘
π₯ = ππ₯(ππ‘)
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Large country
πΈ ΰΆ±0
β
πβππ‘ log ππ‘β ππ‘
Consumption Cobb-Douglas preferences(over 1 non-tradable one 2 tradable goods)
π0,π‘β (1βπΌ)
(π1,π‘β )π½(π2,π‘
β )(1βπ½)πΌ
Investment rate πβ in terms of non-tradable local good
Evolution of physical capital stockπππ‘
β
ππ‘β = Ξ¦ πβ βπΏ ππ‘
Output shocks per unit of capital πβ, π1,π‘β , or π2,π‘
β
β’ Determines relative pricesβ’ β¦ has to be indifferent Ito-processes
Idiosyncratic real cash flow shocks πππ‘βπ ΰ·¨ππ‘
πβ
Net worth dynamics: πππ‘
β
ππ‘β = ππ‘
βππβππ‘ + (1 β ππ‘)ππΎβππ‘ β
ππ‘β
ππ‘β ππ‘ + π
ππ‘β
ππ‘β π ΰ·¨ππ‘
πβ +ππ‘β
ππ‘β ππ‘
Value of output of all goods produced πβπΎπ‘β N
um
erai
re is
no
n-
trad
able
loca
l go
od
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Non-tradeable to consumption basket
Tradeable, non-tradeable good 1 and 2β’ πβ units of non-tradeable good buy
π1,π‘β of tradeable good, or
πβ 1βπΌ π1,π‘β πΌπ½
π2,π‘β πΌ(1βπ½)
units of the βaggregate goodβ (consumption basket).
β’ Hence, production of consumption basket is
πβ β ππ‘β ππ‘
β πΌπΎπ‘β, with ππ‘
β =π1,π‘β π½
π2,π‘β 1βπ½
πβ
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Return on global money ($)
In terms of non-tradable local good (as numeraire)(which is used for investment rate ππ‘
β)
πβππ‘ = Ξ¦ πβ β πΏ ππ‘ is risk free
Change of numeraireIn terms of tradable basket (change of numeraire)
ππ‘πΊ β‘ πβππ‘ + πππ‘
β
ππ‘β
β’ Where price of non-tradable good in terms of tradable basket
ππ‘β =
π1,π‘β π½
π2,π‘β 1βπ½
πβ
β’ Special case: π1,π‘β π½
π2,π‘β 1βπ½
and hence ππ‘β is constant
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Solving
1. Postulateβ’ Price processes πππ‘
β/ππ‘β = ππ‘
πβππ‘ + ππβπππ‘
β, πππ‘β/ππ‘
β= β―β’ Portfolio processes πππ‘
β/ππ‘β
2. Derive return processesβ’ πππΎβ = Ξ¦ πβ β πΏ ππ‘ + πββπβ
πππ‘ + π
ππ ΰ·¨ππ‘
β’ πππβ = Ξ¦ πβ β πΏ ππ‘ β (ππββπππβ)ππ‘
3. Optimality conditions & Market clearing conditions
4. Solve βundetermined coefficientsβ (ππ₯ π π‘ , ππ₯(π π‘))
β’ Solving ODE with boundary conditionsβ’ For large country: simply solve for constants
money supply growth rate that is NOT distributed via interest payment
Set πππβ = 0
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Solving
1. Postulateβ’ Price processes ππ‘
β, ππ‘β
β’ Portfolio processes ππ‘β
2. Derive return processesβ’ πππΎβ = Ξ¦ πβ β πΏ ππ‘ + πββπβ
πππ‘ + π
ππ ΰ·¨ππ‘
β’ πππβ = Ξ¦ πβ β πΏ ππ‘ β (ππββπππβ)ππ‘
3. Optimality conditions & Market clearing conditions
4. Solve βundetermined coefficientsβ (ππ₯ π π‘ , ππ₯(π π‘))
β’ Solving ODE with boundary conditionsβ’ For large country: simply solve for constants
Simply constants for large country
money supply growth rate that is NOT distributed via interest payment
Set πππβ = 0
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Optimality (=) & market clearing (=)
Investment rate, πβ
β’ Tobinβs q: Ξ¦β² πβ =1
πβ(static problem)
For Ξ¦ πβ = 1
π log(π πβ + 1) β π πβ = πβ β 1
Portfolio choice, πβ
β’ πΈ πππΎβ β πππβ /ππ‘ = πΆππ£[πππΎβ β πππβ,ΰΈπππ‘
β
ππ‘β
πππβ+(1βπβ) πππΎββπππβ
] = (1 β πβ)( πβ/π)2
1 β πβ =πΈ πππΎββπππβ /ππ‘
(πβ/πβ)2= (πββπβ)/πβ+ππβ
(πβ/πβ)2= πβ
πβ+πβ
β’ Dividend yield on capital must be π
Consumptionβ’ Demand πππ‘
β = π πβ + πβ πΎπ‘β = πβ β πβ πΎπ‘
β Supply
πβ =πβ
πβ + πβ
=1βπβ
(πβ β πβ)/π
Output market clearing
Capital market clearing
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Equilibrium
where ΖΈππβ = 1 β πβ
ππππ‘πππππ π βπππ
ππβ (monotone transformation)
Numeraire is local good
Moneyless equilibrium Money equilibrium
π0β = 0 πβ = πβ(1+π π)
π+ΰ·ππββ(1+π πβ)
π0β = πβ
π+ΰ·ππβπβ = 1+π πβ β
π ππβ
π+ΰ·ππβ>
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Optimal Monetary Policy
Money growth π affects inflation in two ways
π = ππβ β (Ξ¦ πβ ππβ β ππ,πβ β πΏ)
π
MoPo can correct pecuniary externality β’ Citizens take real interest rate as given
when choosing their portfolio between money & physical capitalβ’ Money exists for πβ > πβ’ Money growth > 0 is optimal for πβ > 2 π (for π = 0)
β’ MoPo improves insurance provided by βsafe assetβ Constrained optimal! Incentive compatible
Money is neither neutral nor super-neutral (no price stickiness)
boosts growth like in Tobin (1965)
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Overview
Large countryβ’ Portfolio choice between
Physical capital ππ‘β
US Dollar, $ β βbubble in positive net supplyβ
β’ No state variable: due to scale invariance
Small countryβ’ Portfolio choice between
Physical capital ππ‘ Peso βhedge against idiosyncratic shocksβ
US Dollar, $ βhedge against ToT + export productivity shocksβ
β’ State variable ππ‘:Accumulation dynamics of foreign asset position (in $)
ππ‘π₯ = ππ₯ ππ‘ , ππ‘
π₯ = ππ₯(ππ‘)
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Small country
Small country cannot produce tradable good 2
tradable basket can be traded for global good 1 at rate
ππ‘ β ΰΈπ1,π‘Productivity
π2,π‘β /π1,π‘
β 1βπ½
Terms of Trade
=π1,π‘π1,π‘β ( π1,π‘
β π½π2,π‘β 1βπ½
)
β’ Short-cut thinking:one unit of capital produces ππ‘ units of tradable basket(while actually it produces only good 1 at rate π1 and trades some of them for tradable good 2)
πππ‘
ππ‘= ππππ‘ + πππππ‘
since all π1,π‘, π2,π‘β , π1,π‘
β are (correlated) geometric Brownian.
Return on global money can be written as
πππ‘πΊ = ππΊππ‘ + ππΊπππ‘ + ππΊ,βπππ‘
β
call prefer
Ito product rule: π ππ‘ππ‘ = πππ‘ππ‘ + ππ‘πππ‘ + ππππππ‘
Part of ππ‘β which is orthogonal to ππ‘
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Small country
Same preferences:
β’ πΈ 0βπβππ‘ log ππ‘ ππ‘
β’ π0,π‘(1βπΌ)
π1,π‘π½π2,π‘1βπ½ πΌ
ΰ·πΌπ‘πΎπ‘ devoted to produce tradable good 1β’ Can be traded for tradable basket since
small county canβt produce tradable good 2 itself
ππ‘ππ‘πΎπ‘ consumption of tradable goods basket
( ΰ·πΌπ‘βππ‘)ππ‘πΎπ‘ trade-imbalance (net export)
πΊπ‘ > 0 Net foreign asset position (only global money)
(in tradable goods basket)
ππΊπ‘πΊπ‘
= πππ‘πΊ + (ΰ·πΌπ‘βππ‘)ππ‘πΎπ‘
πΊπ‘ππ‘
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State variable
Equilibrium is a map
Histories of shocks prices ππ‘ , ππ‘, allocationππ, ππ
β, 0 β€ π β€ π‘ ΰ·πΌπ‘, ππ‘, ππ‘ & portfolio (1 β ππ‘ β ππ‘, ππ‘, ππ‘)
net foreign asset position to tradable production potential
ππ‘ =πΊπ‘
ππ‘πΎπ‘
Evolution
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Portfolio choice & Asset pricing
Portfolio share (processes)
β’ Local moneyπππ‘ππ‘
=ππ‘πππ‘+ππ‘
ππππ‘+ππ‘π,βπππ‘
β
β’ Global moneyπππ‘
ππ‘= ππ‘
πππ‘ + ππ‘
ππππ‘ + ππ‘
π,βπππ‘
β
Returns expressed with country networth, ππ‘, as numeraireβ’ Return on individual networth πππ‘
π = πππ‘ + (1 β ππ‘ β ππ‘)ππ
π(ππ‘)
β’ Return on local money πππ‘ππΏ =
πππ‘
ππ‘
β’ Return on global money ($) πππ‘ππΊ =
ΰ·πΌπ‘βππ‘
ππ‘ππ‘ +
πππ‘
ππ‘
Asset pricing equation (due to log utility)
πΈ πππ‘π β πππ‘
ππΊ = πΆππ£[πππ‘π β πππ‘
ππΊ , πππ‘π] β π β
ΰ·πΌπ‘βππ‘
ππ‘β ππ‘
π= ππ 2
πΈ πππ‘π β πππ‘
ππΏ = πΆππ£[πππ‘π β πππ‘
ππΏ , πππ‘π] β π β ππ‘
π = ππ 2
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Portfolio choice & Asset pricing
Portfolio share (processes)
β’ Local moneyπππ‘ππ‘
=ππ‘πππ‘+ππ‘
ππππ‘+ππ‘π,βπππ‘
β
β’ Global moneyπππ‘
ππ‘= ππ‘
πππ‘ + ππ‘
ππππ‘ + ππ‘
π,βπππ‘
β
Returns expressed with country net worth ππ‘ as numeraireβ’ Return on individual net worth πππ‘
π = πππ‘ + (1 β ππ‘ β ππ‘)ππ
π(ππ‘)
β’ Return on local money πππ‘ππΏ =
πππ‘
ππ‘
β’ Return on global money ($) πππ‘ππΊ =
ππ‘βΰ·πΌπ‘
ππ‘ππ‘ +
πππ‘
ππ‘
Asset pricing equation (due to log utility)
πΈ πππ‘π β πππ‘
ππΊ = πΆππ£[πππ‘π β πππ‘
ππΊ , πππ‘π] β π β
ΰ·πΌπ‘βππ‘
ππ‘β ππ‘
π= ππ 2
πΈ πππ‘π β πππ‘
ππΏ = πΆππ£[πππ‘π β πππ‘
ππΏ , πππ‘π] β π β ππ‘
π = ππ 2
Money worth π net worths
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Portfolio choice & Asset pricing
Portfolio share (processes)β’ Local money
πππ‘ππ‘
=ππ‘πππ‘+ππ‘
ππππ‘+ππ‘π,βπππ‘
β
β’ Global moneyπππ‘
ππ‘= ππ‘
πππ‘ + ππ‘
ππππ‘ + ππ‘
π,βπππ‘
β
Returns expressed with country net worth ππ‘ as numeraireβ’ Return on individual
net worth πππ‘π = πππ‘ + 1 β ππ‘ β ππ‘
ππ
π ππ‘ π ΰ·¨ππ‘
β’ Return on local money πππ‘ππΏ =
πππ‘
ππ‘
β’ Return on global money ($) πππ‘ππΊ =
ππ‘βΰ·πΌπ‘
ππ‘ππ‘ +
πππ‘
ππ‘
Asset pricing equation (due to log utility)
πΈ πππ‘π β πππ‘
ππΏ = πΆππ£[πππ‘π β πππ‘
ππΏ , πππ‘π] β π β ππ‘
π = ππ 2
πΈ πππ‘π β πππ‘
ππΊ = πΆππ£[πππ‘π β πππ‘
ππΊ , πππ‘π] β π β
ππ‘βΰ·πΌπ‘
ππ‘β ππ‘
π= ππ 2
E[net worth β money return]
Price of risk Γ risk
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Consumption & Investment
Consumption Demand π ΰΈπΊπ‘ππ‘
wealthin trad.basket
= ππ‘ππ‘πΎπ‘πΌ
Supply
β’ Cobb-Douglas βconstant consumption expenditure shares
ππ‘ππ‘πΎπ‘πΌ
ππ‘π= [ 1βΰ·πΌπ‘ πβππ‘]
1βπΌππ‘π
Production allocation
Investment rate ππ‘β’ Depends on ππ‘
Output of non-tradableConsumption of tradables
Non-tradable
Trade-able
(incl. net exports)
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(Co-)Existence of Money
Proposition 1:β’ If π2 > π and M β€ Ξ¦ ππ=0 , then
local money has value and π = 0 (no NFAP) is absorbing state
β’ Otherwise, if π2 β π +MβΞ¦ ππ=0 > 0, then global money has value for citizens in small country(and local money may or may not have value)
π2π
M βΞ¦ π =
ππΊ β ππ + ππ β ππΊ ππ
βΞ¦ π + πΏattractiveness of globalmoney
ONLYLOCAL MONEYin the long run
GLOBAL MONEY+ possiblyLOCAL MONEY
attractiveness of local money
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Numerical Example
π = 5%, π = .3, πΌ = .2, ππ = 1%, ππ = .15, ππΊ = 2.2%, π = .13,πΏ = 2%, ππΊ = ππΊ,β = 0, π = 2 β π = .0545, ππ = .15
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Exchange rate dynamics - UIP
ππ‘β β ππ‘ = πΈπ‘ Ξβ° + ππ‘
ππ‘ = ΰΈβππ
>0
(ππ β ππ)>0
(risk premium in terms of Peso)
For ππ‘ = ππ‘β (= 0)
β’ foreign currency is expected to appreciate relative to local currency (whenever it is held in positive quantity). Local currency is a hedge, it appreciates relative to net worth when π drops. Global currency is risky, so to be held in positive amount it must earn a risk
premium
UIP violation, ππ‘, depends whether money is βprintedββ’ to pay interest πππ
No real changes (portfolio choice is not affected) Higher inflation π = πππ β (π π β πΏ), πΈπ‘ Ξβ° = πππ (dollar appreciates)
β’ to generate seignorage (redistributed β wealth share) (ππβπππ) Affects portfolio choice, π, investment rate π, growth rate
risk premium ππ‘
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Flight to safety (into dollar)
Unanticipated increase in ππ
β’ E.g. ToT becomes more volatile
Portfolio share held in dollars increases Dollar valuation is higher
(increase in volatility of π)
Transitionβ’ Start with current (dollar holding) πΊ
β’ Recalculate new state variable ππ‘β’ Our full dynamics also includes transition dynamics
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Spillover from lower ππΊ
β’ Higher money supply growth ππβ in large countryβ’ Lower growth Ξ¦ πβ β πΏ in large countryβ’ Loss of competitive edge in global tradable basket
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Higher Peso inflation ππ‘
seniorage ππ β πππ is distributed β capital holding
Store of value is less attractive β’ Pricing equation now
π + ππ‘ β ππ = ππ 2
higher investment ππ‘ β boosts growth, but higher idio risk
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Mundell-Fleming Trilemma
Trilemma: Can only pick a 2 desiderata out of 3 β1 side
βDilemmaβ: Pick only 1
Autonomous Monetary Policy
Fixed ex-change rate
Free Capital Flow
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Mundell-Fleming Trilemma
Trilemma: Can only pick a 2 desiderata out of 3 β1 side
βDilemmaβ: Pick only 1
Autonomous Monetary Policy
Fixed ex-change rate
Free Capital Flow
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Floating Exchange Rate
With floating exchange rate & open capital account Still range of Monetary policy, since local and global money are imperfect substitutes
β’ Inflation boosts growth, but only possible up to a limit ΰ΄€π(ππΊ). Beyond ΰ΄€π(ππΊ) monetary policy has little bite Global money becomes too attractive
β’ Range is higher with higher inflation in large country (global money) Large countryβs MoPo determines
range for small country
Policy range is largerif local money is backed by taxes(ΰ΄€π depends on distribution of seignorage)
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Closed capital account
Range of Monetary policy is much larger,up ധπ = π2 β π β 4%(physical capital is risky store of value)
Total money holding is larger with closed capital accountβ’ Global money would be a better
hedge for βexport riskβ
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Fixed exchange rate regimes & no MoPo
Dollarization = (fully backed) Currency Board Xx
Exchange rate pegβ’ Requires strong fiscal backing
(since no backing through holding of global reserves) After a string of adverse shocks, government must tax and use to
proceeds to remove some of the local currency in circulation
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Foreign Currency Reserves
Irrelevance Theorem:β’ If central bank holds global money (reserves)
β’ Citizens in small country will hold accordingly less
Remark:β’ If central banks holds more $-reserves than citizens would like to
hold, then agents borrow foreign currency from abroad.
β’ If local money is worthless (without foreign reserves), then the value of local money with reserves only derives from the latter (currency board)
β’ With fiscal backing of the local money, complicates analysis
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Optimal Monetary Policy
LARGE COUNTRYMoPo can correct pecuniary externality β’ Citizens take real interest rate as given
when choosing their portfolio between money & physical capitalβ’ Money exists for πβ > πβ’ Inflation is optimal for πβ > 2 π
β’ MoPo improves insurance provided by βsafe assetβ Constrained optimal! Incentive compatible
SMALL COUNTRYβ’ Additional savings decision due open capital account
Generally, optimal monetary policy depends on control social planner has
(For π = 0, no adjustment costs)
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Conclusion
Endogenous value of money (safe asset) in 2 countriesβ’ Local currency: better hedge for idiosyncratic risk (non-tradable consumption)
β’ Global currency: hedge against ToT + export productivity shocks
Spillover effects from US monetary policy
Flight to safety
When to peg? When to dollarize?
βNuanced Mundell-Fleming Trilemmaββ’ Local and global money have different risk profile (imperfect substitutes)
β increases MoPo space β’ Too high Peso inflation:
local citizens substitute local currency for global currencyβ limits MoPo space
Central Bankβs foreign reserves holding: Irrelevance Result
Optimal Monetary Policy β’ Idiosyncratic risk β correct pecuniary externality (real interest rate)β’ International savings