第九章垄断竞争和寡头2

寡头垄断•主要内容:•寡头垄断市场的特点•古诺模型•斯威齐模型•寡头厂商之间的博弈•对寡头垄断市场的评价OligopolyDefined•数量有限的少数企业占据产业的主导地位。•寡头垄断企业的经营战略（行为）相互影响。每一企业在做出行动决策时，都要考虑其他企业将做出的反应。一、寡头垄断市场的条件AtTheSameTime•Giventhesmallnumberoffirms,oligopolistshaveamuchbetterchanceofcolludingthanmonopolisticcompetitors.容易形成共谋•Itisthisstrategicdecisionmakingandpossibilityofcollusivebehaviorthatmakesoligopolysointeresting.AFewQuestions•Inanalyzingoligopoly,whatweultimatelywanttoanswerarethesequestions:–什么因素导致寡头垄断的产生？–寡头垄断市场的功能特征。–这种市场功能有怎样的市场绩效？SourcesOfOligopoly•进入的障碍导致寡头垄断的产生。AC$Output#1:Scale-EconomyBarrierstoEntry•Recallthatwithmonopoly,averagecostsdecreasethroughouttherelevantrangeofproductionsothatonefirmisabletoeventuallydriveoutallotherfirmsbyproducingatlowestcost.•Witholigopoly,itisafewfirms--notjustone–thatdriveeveryoneelseout.MinimumefficientscaleforafirminthisindustryisaplantsizeofAC,whichequalsonethirdofthetotaloutputAD.Aggregatecostsperunitofoutput.OutputABCDconstantreturnstoscaleAverageTotalCostCurveforanOligopolisticindustryMinimumEfficientScale•Thesmallestlevelofoutputatwhichafirmcanminimizelong-runaveragecosts.Inthecaseofnaturalmonopoliesliketherailroadsandutilities,smallfirmscannotrealizetheMES–theminimumefficientscale--sothereisonlyoneseller.•Alargeminimumefficientscalecanalsogiverisetooligopoly.Aggregatecostsperunitofoutput.OutputABCDconstantreturnstoscaleAverageTotalCostCurveforanOligopolisticindustryTheEntryDilemma•AssumethreebigfirmsinthisindustryallproducinganoutputofACattheirMESwithanequalshareofthemarket.•Canyouseethedilemmaforanewfirmtryingtoenterthisindustry?Aggregatecostsperunitofoutput.OutputABCDconstantreturnstoscaleAverageTotalCostCurveforanOligopolisticindustryEasilyForcedOut•IfthenewfirmtriestoentertheindustryataplantsizelessthantheMES–sayatoutputAB--itwillbeahighercostproducerthanitsrivalsandwillbehighlyvulnerabletobeingdrivenoutoftheindustrybyitscompetitors.•Allitsrivalsneedtodoissetpricebelowthenewfirm’scostsforawhile,causeittoincurheavylosses,andeventually,itwillwithdraw.Aggregatecostsperunitofoutput.OutputABCDconstantreturnstoscaleAverageTotalCostCurveforanOligopolisticindustryAlternatively•IfthefirmbuildsaplantsizeattheMEStobecompetitive,itwillhavetoseizeasizeablemarketsharefromitsrivalstoachieveefficientproduction.•Itwouldhavetocuteachofitsrivalsbackfromathirdtoafourthofthenationalmarket;andthelikelyresultwouldbelossesforeveryone.•Itisperhapsnotsurprisingthatscale-economybarriersdeterentryintotheindustryandpreservetheoligopolisticstructure.Aggregatecostsperunitofoutput.OutputABCDconstantreturnstoscaleAverageTotalCostCurveforanOligopolisticindustry•Itsimplyrequiresalotofcapitalinvestmenttosetuptheelaborateplantandequipmentnecessarytoproduce.•Thebroaderproblemisthatestablishedfirmswithatrackrecordmayhavebetteraccesstolowercostcapitalthannewentrants.#2:LargeCapitalRequirementsForExample•Alarge,existingfirmwithanestablishedreputationwilllikelybeabletoborrowmoneyatasignificantlylowerinterestratethananewfirmwithoutatrackrecord.Aggregatecostsperunitofoutput.OutputNewFirmOldfirm#3:AbsoluteCostAdvantange•Onesourceofsuchbarriersisthatestablishedfirmsmaypossessvaluableknow-howinproductionorso-calledtradesecrets.•OneofthebestkeptsecretsintheindustrialworldisthesecretingredientinCocaCola.•Onlyafewexecutivesinthecompanyknowwhatitis.TradeSecretsPatents•Anexistingfirmmayhavepatentsgrantingitexclusiverightstocertainproductfeaturesorproductionprocesses.RawMaterials#4:ProductDifferentiationBarrierstoEntry•Anynewfirmenteringthemarketwouldhavetoincursubstantialadvertisingcostsjusttoenjoythesamesizeandinelasticityofdemandforitsproduct.TheBottomLine•Barrierstoentryplayaveryimportantroleincreatingandsustainingoligopolisticindustries.•Whyshouldweworryaboutthisparticularmarketstructure?•Theanswerliesinbetterunderstandingtheconceptsofmarketpowerandmarketconcentration.MarketPower•Marketpowersignifiesthedegreeofcontrolthatafirmorasmallnumberoffirmshasoverthepriceandproductiondecisionsinanindustry.•Themostcommonmeasureofmarketpoweristhefour-firmconcentrationratio.StrategicInteraction•Concentrationratiosareimportantbecausetheyhelpserveasanindicatorofthedegreeofstrategicinteractionthatmightoccurinanindustry.•Strategicinteractionisatermthatdescribeshoweachfirm’sbusinessstrategydependsontheirrivals’strategies.MutualInterdependenceRecognized•由于产业内部企业数量减少，产业集中度提高，每一企业在进行产量和价格决定时，都要考虑竞争对手由此做出的反应。•一旦这种相互依赖、相互影响的行为机制被认识到，厂商只能在合作和非合作行为中选择其一。NoncooperativeBehavior•当一个厂商与其他厂商没有任何显性和隐性的合约时，厂商的行为是独立的。•Thistypicallycharacterizesmonopolisticcompetition.CooperativeBehavior•为了尽可能减少竞争，厂商间达成有关价格、产量或其他市场运作方面的显性和隐性合约，形成厂商间行为的合作。Collusion•Whenfirmsinanoligopolyactcooperatively,theymustengageinsomeformofcollusion.•当企业联合决定他们的价格、产量或者共同决定各自占有的市场份额时，共谋就产生了。•这种共谋可以是显性的也可以是隐性的。•OneexampleofexplicitcollusionwouldbethatoftheGildedAge（美国镀金时代，南北战争后35年间）oligopolistsintheearlyyearsofAmericancapitalism.•这些寡头垄断者建立托拉斯或者卡特尔以控制价格。ExplicitCollusionTheAntitrustLaws•当美国人认识到需要对垄断进行控制并于1910年通过了反托拉斯法以后，卡特尔等显性的共谋行为就变成了非法行为。TacitCollusion•因为反托拉斯法的限制，显性的共谋行为是非法的，隐性共谋成为一种选择。•Thewordtacitmeansto“expressor