saving_investment 曼昆 微观经济学

26,Saving,Investment,andtheFinancialSystem,TheFinancialSystem,Thefinancialsystemconsistsofthegroupofinstitutionsintheeconomythathelptomatchonepersonssavingwithanotherpersonsinvestment.Itmovestheeconomysscarceresourcesfromsaverstoborrowers.,FINANCIALINSTITUTIONSINTHEU.S.ECONOMY,Thefinancialsystemismadeupoffinancialinstitutionsthatcoordinatetheactionsofsaversandborrowers.Financialinstitutionscanbegroupedintotwodifferentcategories:financialmarketsandfinancialintermediaries.,FINANCIALINSTITUTIONSINTHEU.S.ECONOMY,FinancialMarketsStockMarketBondMarketFinancialIntermediariesBanksMutualFunds,FINANCIALINSTITUTIONSINTHEU.S.ECONOMY,Financialmarketsaretheinstitutionsthroughwhichsaverscandirectlyprovidefundstoborrowers.Financialintermediariesarefinancialinstitutionsthroughwhichsaverscanindirectlyprovidefundstoborrowers.,FinancialMarkets,TheBondMarketAbondisacertificateofindebtednessthatspecifiesobligationsoftheborrowertotheholderofthebond.CharacteristicsofaBondTerm:Thelengthoftimeuntilthebondmatures.CreditRisk:Theprobabilitythattheborrowerwillfailtopaysomeoftheinterestorprincipal.TaxTreatment:Thewayinwhichthetaxlawstreattheinterestonthebond.Municipalbondsarefederaltaxexempt.,FinancialMarkets,TheStockMarketStockrepresentsaclaimtopartialownershipinafirmandistherefore,aclaimtotheprofitsthatthefirmmakes.Thesaleofstocktoraisemoneyiscalledequityfinancing.Comparedtobonds,stocksofferbothhigherriskandpotentiallyhigherreturns.ThemostimportantstockexchangesintheUnitedStatesaretheNewYorkStockExchange,theAmericanStockExchange,andNASDAQ.,FinancialMarkets,TheStockMarketMostnewspaperstocktablesprovidethefollowinginformation:Price(ofashare)Volume(numberofsharessold)Dividend(profitspaidtostockholders)Price-earningsratio,FinancialIntermediaries,Financialintermediariesarefinancialinstitutionsthroughwhichsaverscanindirectlyprovidefundstoborrowers.,FinancialIntermediaries,Bankstakedepositsfrompeoplewhowanttosaveandusethedepositstomakeloanstopeoplewhowanttoborrow.paydepositorsinterestontheirdepositsandchargeborrowersslightlyhigherinterestontheirloans.,FinancialIntermediaries,BanksBankshelpcreateamediumofexchangebyallowingpeopletowritechecksagainsttheirdeposits.Amediumofexchangesisanitemthatpeoplecaneasilyusetoengageintransactions.Thisfacilitatesthepurchasesofgoodsandservices.,FinancialIntermediaries,MutualFundsAmutualfundisaninstitutionthatsellssharestothepublicandusestheproceedstobuyaportfolio,ofvarioustypesofstocks,bonds,orboth.Theyallowpeoplewithsmallamountsofmoneytoeasilydiversify.,FinancialIntermediaries,OtherFinancialInstitutionsCreditunionsPensionfundsInsurancecompaniesLoansharks,SAVINGANDINVESTMENTINTHENATIONALINCOMEACCOUNTS,RecallthatGDPisbothtotalincomeinaneconomyandtotalexpenditureontheeconomysoutputofgoodsandservices:Y=C+I+G+NX,SomeImportantIdentities,Assumeaclosedeconomyonethatdoesnotengageininternationaltrade:Y=C+I+G,SomeImportantIdentities,Now,subtractCandGfrombothsidesoftheequation:YCG=ITheleftsideoftheequationisthetotalincomeintheeconomyafterpayingforconsumptionandgovernmentpurchasesandiscallednationalsaving,orjustsaving(S).,SomeImportantIdentities,SubstitutingSforY-C-G,theequationcanbewrittenas:S=I,SomeImportantIdentities,Nationalsaving,orsaving,isequalto:S=IS=YCGS=(YTC)+(TG),TheMeaningofSavingandInvestment,NationalSavingNationalsavingisthetotalincomeintheeconomythatremainsafterpayingforconsumptionandgovernmentpurchases.PrivateSavingPrivatesavingistheamountofincomethathouseholdshaveleftafterpayingtheirtaxesandpayingfortheirconsumption.Privatesaving=(YTC),TheMeaningofSavingandInvestment,PublicSavingPublicsavingistheamountoftaxrevenuethatthegovernmenthasleftafterpayingforitsspending.Publicsaving=(TG),TheMeaningofSavingandInvestment,SurplusandDeficitIfTG,thegovernmentrunsabudgetsurplusbecauseitreceivesmoremoneythanitspends.ThesurplusofT-Grepresentspublicsaving.IfGT,thegovernmentrunsabudgetdeficitbecauseitspendsmoremoneythanitreceivesintaxrevenue.,TheMeaningofSavingandInvestment,Fortheeconomyasawhole,savingmustbeequaltoinvestment.S=I,THEMARKETFORLOANABLEFUNDS,Financialmarketscoordinatetheeconomyssavingandinvestmentinthemarketforloanablefunds.,THEMARKETFORLOANABLEFUNDS,Themarketforloanablefundsisthemarketinwhichthosewhowanttosavesupplyfundsandthosewhowanttoborrowtoinvestdemandfunds.,THEMARKETFORLOANABLEFUNDS,Loanablefundsreferstoallincomethatpeoplehavechosentosaveandlendout,ratherthanusefortheirownconsumption.,SupplyandDemandforLoanableFunds,Thesupplyofloanablefundscomesfrompeoplewhohaveextraincometheywanttosaveandlendout.Thedemandforloanablefundscomesfromhouseholdsandfirmsthatwishtoborrowtomakeinvestments.,SupplyandDemandforLoanableFunds,Theinterestrateisthepriceoftheloan.Itrepresentstheamountthatborrowerspayforloansandtheamountthatlendersreceiveontheirsaving.Theinterestrateinthemarketforloanablefundsistherealinterestrate.,SupplyandDemandforLoanableFunds,Financialmarketsworkmuchlikeothermarketsintheeconomy.Theequilibriumofthesupplyanddemandforloanablefundsdeterminestherealinterestrate.,Figure1TheMarketforLoanableFunds,LoanableFunds,(inbillionsofdollars),0,Interest,Rate,Copyright2004South-Western,SupplyandDemandforLoanableFunds,GovernmentPoliciesThatAffectSavingandInvestmentTaxesandsavingTaxesandinvestmentGovernmentbudgetdeficits,Policy1:SavingIncentives,Taxesoninterestincomesubstantiallyreducethefuturepayofffromcurrentsavingand,asaresult,reducetheincentivetosave.,Policy1:SavingIncentives,Ataxdecreaseincreasestheincentiveforhouseholdstosaveatanygiveninterestrate.Thesupplyofloanablefundscurveshiftstotheright.Theequilibriuminterestratedecreases.Thequantitydemandedforloanablefundsincreases.,Figure2AnIncreaseintheSupplyofLoanableFunds,LoanableFunds,(inbillionsofdollars),0,Interest,Rate,Copyright2004South-Western,Policy1:SavingIncentives,Ifachangeintaxlawencouragesgreatersaving,theresultwillbelowerinterestratesandgreaterinvestment.,Policy2:InvestmentIncentives,Aninvestmenttaxcreditincreasestheincentivetoborrow.Increasesthedemandforloanablefunds.Shiftsthedemandcurvetotheright.Resultsinahigherinterestrateandagreaterquantitysaved.,Policy2:InvestmentIncentives,Ifachangeintaxlawsencouragesgreaterinvestment,theresultwillbehigherinterestratesandgreatersaving.,Figure3AnIncreaseintheDemandforLoanableFunds,LoanableFunds,(inbillionsofdollars),0,Interest,Rate,Copyright2004South-Western,Policy3:GovernmentBudgetDeficitsandSurpluses,Whenthegovernmentspendsmorethanitreceivesintaxrevenues,theshortfalliscalledthebudgetdeficit.Theaccumulationofpastbudgetdeficitsiscalledthegovernmentdebt.,Policy3:GovernmentBudgetDeficitsandSurpluses,Governmentborrowingtofinanceitsbudgetdeficitreducesthesupplyofloanablefundsavailabletofinanceinvestmentbyhouseholdsandfirms.Thisfallininvestmentisreferredtoascrowdingout.Thedeficitborrowingcrowdsoutprivateborrowerswhoaretryingtofinanceinvestments.,Policy3:GovernmentBudgetDeficitsandSurpluses,Abudgetdeficitdecreasesthesupplyofloanablefunds.Shiftsthesupplycurvetotheleft.Increasestheequilibriuminterestrate.Reducestheequilibriumquantityofloanablefunds.,Figure4:TheEffectofaGovernmentBudgetDeficit,LoanableFunds,(inbillionsofdollars),0,Interest,Rate,Copyright2004South-Western,Policy3:GovernmentBudgetDeficitsandSurpluses,Whengovernmentreducesnationalsavingbyrunningadeficit,theinterestraterisesandinvestmentfalls.,Policy3:GovernmentBudgetDeficitsandSurpluses,Abudgetsurplusincreasesthesupplyofloanablefunds,reducestheinterestrate,andstimulatesinvestment.,Figure5TheU.S.GovernmentDebt,Percent,ofGDP,1790,1810,1830,1850,1870,1890,1910,1930,1950,1970,1990,2010,0,20,40,60,80,100,120,Copyright2004South-Western,Summary,TheU.S.financialsystemismadeupoffinancialinstitutionssuchasthebondmarket,thestockmarket,banks,andmutualfunds.Alltheseinstitutionsac