第 市场势力垄断与买方垄断

会计学1第市场势力垄断与买方垄断Slide2本章要讨论的问题买方垄断买方垄断势力限制市场势力:反垄断法第1页/共100页Slide3完全竞争完全竞争回顾P=LMC=LRAC长期内只存在正常利润或经济利润为零大量生产者和消费者同质化产品充分信息企业是价格的接受者第2页/共100页完全竞争QQPP市场单个企业DSQ0P0P0D=MR=Pq0LRACLMC第3页/共100页Slide5完全垄断完全垄断 1) 一个生产者–许多消费者 2) 一种产品(没有替代品) 3) 市场进入壁垒第4页/共100页Slide6完全垄断完全垄断企业是市场供给方，对其产品的销售能够绝对控制。当边际收入等于边际成本时，利润达到最大。第5页/共100页Slide7完全垄断确定边际收入作为唯一的生产者,垄断企业面对整个市场假定企业的需求为:P=6-Q第6页/共100页Slide8总收入、边际收入及平均收入 $6 0 $0 --- --- 5 1 5 $5 $5 4 2 8 3 4 3 3 9 1 3 2 4 8 -1 2 1 5 5 -3 1

价格 数量总收入 边际收入平均收入

P Q TR MR AR第7页/共100页Slide9平均收入和边际收入Q0123P12345674567平均收入(需求)边际收入第8页/共100页Slide10完全垄断观察 1) 只有降价才能增加销售量 2) MR<P

3) 与完全竞争比较不需要降价就能增加销售量MR=P第9页/共100页Slide11完全垄断完全垄断企业的产量决策

当MR=MC时利润达到最大化

或第10页/共100页Slide12利润最大化当产量低于MR=MC时，收入的减少大于成本的减少(MR>MC).当产量高于MR=MC时，收入的增加小于成本的增加(MR<MC)完全垄断企业的产量决策第11页/共100页Slide13利润减少P1Q1利润减少MCACQPD=ARMRP*Q*利润最大化P2Q2第12页/共100页Slide14完全垄断定价法则可以将边际收入等于边际成本的原理转化为一个简单实用的法则其过程可说明如下:第13页/共100页Slide15定价法则第14页/共100页Slide16定价法则第15页/共100页Slide17定价法则第16页/共100页Slide18=边际成本加价在价格中所占比例【(P-MC)/P】定价法则8.加价等于需求价格弹性的倒数。

第17页/共100页Slide19定价法则假设：第18页/共100页Slide20完全垄断完全垄断与完全竞争的价格比较:完全垄断P>MC完全竞争P=MC第19页/共100页Slide21完全垄断完全垄断与完全竞争的价格比较:需求价格弹性越大，价格越接近于边际成本第20页/共100页Slide22完全垄断需求变化在完全竞争市场中,市场供给曲线由边际成本决定；对于完全垄断企业,产量由边际成本和需求曲线共同决定；第21页/共100页Slide23D2MR2D1MR1需求变动导致价格变动但产量不变QMCPP2P1Q1=Q2第22页/共100页Slide24D1MR1需求变动导致产量变动但价格不变MCPMR2D2P1=P2Q1Q2Q第23页/共100页Slide25完全垄断观察需求变化通常导致价格及需求量都发生变化；完全垄断市场没有供给曲线；第24页/共100页Slide26完全垄断观察在相同价格水平下，完全垄断企业可能生产不同数量的产品；在不同价格水平下，完全垄断企业可能生产相同数量的产品；第25页/共100页Slide27MonopolyTheEffectofaTaxUndermonopolypricecansometimesrisebymorethantheamountofthetax.Todeterminetheimpactofatax:t=specifictaxMC=MC+tMR=MC+t:optimalproductiondecision第26页/共100页Slide28EffectofExciseTaxonMonopolistQuantity$/QMCD=ARMRQ0P0MC+taxtQ1P1IncreaseinP:P0P1>increaseintax第27页/共100页Slide29QuestionSuppose:Ed=-2Howmuchwouldthepricechange?EffectofExciseTaxonMonopolist第28页/共100页Slide30AnswerWhatwouldhappentoprofits?EffectofExciseTaxonMonopolist第29页/共100页Slide31MonopolyTheMultiplantFirmFormanyfirms,productiontakesplaceintwoormoredifferentplantswhoseoperatingcostcandiffer.第30页/共100页Slide32MonopolyTheMultiplantFirmChoosingtotaloutputandtheoutputforeachplant:Themarginalcostineachplantshouldbeequal.Themarginalcostshouldequalthemarginalrevenueforeachplant.第31页/共100页Slide33MonopolyAlgebraically:TheMultiplantFirm第32页/共100页Slide34MonopolyAlgebraically:TheMultiplantFirm第33页/共100页Slide35MonopolyAlgebraically:TheMultiplantFirm第34页/共100页Slide36MonopolyAlgebraically:第35页/共100页Slide37ProductionwithTwoPlantsQuantity$/QD=ARMRMC1MC2MCTMR*Q1Q2Q3P*第36页/共100页Slide38ProductionwithTwoPlantsObservations: 1) MCT=MC1+MC2 2) Profitmaximizing output:MCT=MRatQTandP*MR=MR*MR*=MC1atQ1,MC*=MC2atQ2MC1+MC2=MCT,Q1+Q2=QT,andMR=MC1+MC2

Quantity$/QD=ARMRMC1MC2MCTMR*Q1Q2Q3P*第37页/共100页Slide39MonopolyPowerMonopolyisrare.However,amarketwithseveralfirms,eachfacingadownwardslopingdemandcurvewillproducesothatpriceexceedsmarginalcost.第38页/共100页Slide40MonopolyPowerScenario:Fourfirmswithequalshare(5,000)ofamarketfor20,000toothbrushesatapriceof$1.50.第39页/共100页Quantity10,0002.00QA$/Q$/Q1.501.0020,00030,0003,0005,0007,0002.001.501.001.401.60Atamarketpriceof$1.50,elasticityofdemandis-1.5.MarketDemandTheDemandforToothbrushesThedemandcurveforFirmAdependsonhowmuchtheirproductdiffers,andhowthefirmscompete.第40页/共100页Atamarketpriceof$1.50,elasticityofdemandis-1.5.Quantity10,0002.00QA$/Q$/Q1.501.0020,00030,0003,0005,0007,0002.001.501.001.401.60DAMRAMarketDemandFirmAseesamuchmoreelasticdemandcurveduetocompetition--Ed=-.6.StillFirmAhassomemonopolypowerandchargesapricewhichexceedsMC.MCATheDemandforToothbrushes第41页/共100页Slide43MonopolyPowerMeasuringMonopolyPowerInperfectcompetition:P=MR=MCMonopolypower:P>MC第42页/共100页Slide44MonopolyPowerLerner’sIndexofMonopolyPowerL=(P-MC)/PThelargerthevalueofL(between0and1)thegreaterthemonopolypower.LisexpressedintermsofEdL=(P-MC)/P=-1/EdEd

iselasticityofdemandforafirm,notthemarket第43页/共100页Slide45MonopolyPowerMonopolypowerdoesnotguaranteeprofits.Profitdependsonaveragecostrelativetoprice.Question:CanyouidentifyanydifficultiesinusingtheLernerIndex(L)forpublicpolicy?第44页/共100页Slide46MonopolyPowerTheRuleofThumbforPricingPricingforanyfirmwithmonopolypowerIfEdislarge,markupissmallIfEd

issmall,markupislarge第45页/共100页ElasticityofDemandandPriceMarkup$/Q$/QQuantityQuantityARMRMRARMCMCQ*Q*P*P*P*-MCThemoreelasticisdemand,thelessthemarkup.第46页/共100页Slide48MarkupPricing:

SupermarketstoDesignerJeansSupermarkets第47页/共100页Slide49ConvenienceStoresMarkupPricing:

SupermarketstoDesignerJeans第48页/共100页Slide50Conveniencestoreshavemoremonopolypower.Question:Doconveniencestoreshavehigherprofitsthansupermarkets?MarkupPricing:

SupermarketstoDesignerJeansConvenienceStores第49页/共100页Slide51DesignerjeansEd=-3to-4Price33-50%>MCMC=$12-$18/pairWholesaleprice=$18-$27MarkupPricing:

SupermarketstoDesignerJeansDesignerJeans第50页/共100页ThePricingof

PrerecordedVideocassettes 1985 1999

Title RetailPrice($) Title RetailPrice($)PurpleRain $29.98 AustinPowers $10.49RaidersoftheLostArk 24.95 ABug’sLife 17.99JaneFondaWorkout 59.95 There’sSomething aboutMary 13.99TheEmpireStrikesBack 79.98 Tae-BoWorkout 24.47AnOfficerandaGentleman 24.95 LethalWeapon4 16.99StarTrek:TheMotionPicture 24.95 MeninBlack 12.99StarWars 39.98 Armageddon 15.86第51页/共100页WhatDoYouThink?Shouldproducerslowerthepriceofvideocassettestoincreasesalesandrevenue?ThePricingof

PrerecordedVideocassettes第52页/共100页Slide54SourcesofMonopolyPowerWhydosomefirm’shaveconsiderablemonopolypower,andothershavelittleornone?Afirm’smonopolypowerisdeterminedbythefirm’selasticityofdemand.第53页/共100页Slide55SourcesofMonopolyPowerThefirm’selasticityofdemandisdeterminedby: 1) Elasticityofmarketdemand 2) Numberoffirms 3)Theinteractionamongfirms第54页/共100页Slide56TheSocialCostsofMonopolyPowerMonopolypowerresultsinhigherpricesandlowerquantities.However,doesmonopolypowermakeconsumersandproducersintheaggregatebetterorworseoff?第55页/共100页Slide57BALostConsumerSurplusDeadweightLossBecauseofthehigherprice,consumersloseA+BandproducergainsA-C.CDeadweightLossfromMonopolyPowerQuantityARMRMCQCPCPmQm$/Q第56页/共100页Slide58RentSeekingFirmsmayspendtogainmonopolypowerLobbyingAdvertisingBuildingexcesscapacityTheSocialCostsofMonopolyPower第57页/共100页Slide59Theincentivetoengageinmonopolypracticesisdeterminedbytheprofittobegained.Thelargerthetransferfromconsumerstothefirm,thelargerthesocialcostofmonopoly.TheSocialCostsofMonopolyPower第58页/共100页Slide60Example1996ArcherDanielsMidland(ADM)successfullylobbiedforregulationsrequiringethanolbeproducedfromcornQuestionWhyonlycorn?TheSocialCostsofMonopolyPower第59页/共100页Slide61PriceRegulationRecallthatincompetitivemarkets,priceregulationcreatedadeadweightloss.Question:Whataboutamonopoly?TheSocialCostsofMonopolyPower第60页/共100页Slide62ARMRMCPmQmACP1Q1MarginalrevenuecurvewhenpriceisregulatedtobenohigherthatP1.Ifleftalone,amonopolistproducesQmandchargesPm.IfpriceisloweredtoP3outputdecreasesandashortageexists.ForoutputlevelsaboveQ1,theoriginalaverageandmarginalrevenuecurvesapply.IfpriceisloweredtoPCoutputincreasestoitsmaximumQCandthereisnodeadweightloss.PriceRegulation$/QQuantityP2=PCQcP3Q3Q’3AnypricebelowP4resultsinthefirmincurringaloss.P4第61页/共100页Slide63NaturalMonopolyAfirmthatcanproducetheentireoutputofanindustryatacostlowerthanwhatitwouldbeiftherewereseveralfirms.TheSocialCostsofMonopolyPower第62页/共100页Slide64RegulatingthePrice

ofaNaturalMonopoly$/QNaturalmonopoliesoccurbecauseofextensiveeconomiesofscaleQuantity第63页/共100页Slide65MCACARMR$/QQuantitySettingthepriceatPr

yieldsthelargestpossibleoutput;excessprofitiszero.QrPrPCQCIfthepricewereregulatetobePC,thefirmwouldlosemoneyandgooutofbusiness.PmQmUnregulated,themonopolistwouldproduceQmandchargePm.RegulatingthePrice

ofaNaturalMonopoly第64页/共100页Slide66RegulationinPracticeItisverydifficulttoestimatethefirm'scostanddemandfunctionsbecausetheychangewithevolvingmarketconditionsTheSocialCostsofMonopolyPower第65页/共100页Slide67RegulationinPracticeAnalternativepricingtechnique---rate-of-returnregulationallowsthefirmstosetamaximumpricebasedontheexpectedrateorreturnthatthefirmwillearn.P=AVC+(D+T+sK)/Q,whereP=price,AVC=averagevariablecostD=depreciation,T=taxess=allowedrateofreturn,K=firm’scapitalstockTheSocialCostsofMonopolyPower第66页/共100页Slide68RegulationinPracticeUsingthistechniquerequireshearingstoarriveattherespectivefigures.Thehearingprocesscreatesaregulatorylagthatmaybenefitproducers(1950s&60s)orconsumers(1970s&80s).QuestionWhoisbenefitinginthe1990s?TheSocialCostsofMonopolyPower第67页/共100页Slide69MonopsonyAmonopsonyisamarketinwhichthereisasinglebuyer.Anoligopsonyisamarketwithonlyafewbuyers.Monopsonypoweristheabilityofthebuyertoaffectthepriceofthegoodandpaylessthanthepricethatwouldexistinacompetitivemarket.第68页/共100页Slide70MonopsonyCompetitiveBuyerPricetakerP=Marginalexpenditure=AverageexpenditureD=Marginalvalue第69页/共100页CompetitiveBuyer

ComparedtoCompetitiveSellerQuantityQuantity$/Q$/QAR=MRD=MVME=AEP*Q*ME=MVatQ*ME=P*P*=MVP*Q*MCMR=MCP*=MRP*=MCBuyerSeller第70页/共100页Slide72MES=AEThemarketsupplycurveisthemonopsonist’saverageexpenditurecurveMonopsonistBuyerQuantity$/QMVQ*mP*mMonopsonyME>P&aboveSPCQCCompetitiveP=PCQ=Q+C第71页/共100页Slide73MonopolyandMonopsonyQuantityARMRMC$/QQCPCMonopolyNote:MR=MC;AR>MC;P>MCP*Q*第72页/共100页Slide74MonopolyandMonopsonyQuantity$/QMVMES=AEQ*P*PCQCMonopsonyNote:ME=MV;ME>AE;MV>P第73页/共100页Slide75MonopolyandMonopsonyMonopolyMR<PP>MCQm<QCPm>PCMonopsonyME>PP<MVQm<QCPm<PC第74页/共100页Slide76MonopsonyPowerAfewbuyerscaninfluenceprice(e.g.automobileindustry).Monopsonypowergivesthemtheabilitytopayapricethatislessthanmarginalvalue.第75页/共100页Slide77MonopsonyPowerThedegreeofmonopsonypowerdependsonthreesimilarfactors. 1) ElasticityofmarketsupplyThelesselasticthemarketsupply,thegreaterthemonopsonypower.第76页/共100页Slide78MonopsonyPowerThedegreeofmonopsonypowerdependsonthreesimilarfactors. 2) NumberofbuyersThefewerthenumberofbuyers,thelesselasticthesupplyandthegreaterthemonopsonypower.第77页/共100页Slide79MonopsonyPowerThedegreeofmonopsonypowerdependsonthreesimilarfactors. 3) InteractionAmongBuyersThelessthebuyerscompete,thegreaterthemonopsonypower.第78页/共100页MES=AEMES=AEMonopsonyPower:

ElasticversusInelasticSupplyQuantityQuantity$/Q$/QMVMVQ*P*MV-P*P*Q*MV-P*第79页/共100页Slide81ADeadweightLossfrom

MonopsonyPowerDeterminingthedeadweightlossinmonopsonyChangeinseller’ssurplus=-A-CChangeinbuyer’ssurplus=A-BChangeinwelfare=-A-C+A-B=-C-BInefficiencyoccursbecauselessispurchasedQuantity$/QMVMES=AEQ*P*PCQCBCDeadweightLoss第80页/共100页Slide82MonopsonyPowerBilateralMonopolyBilateralmonopolyisrare,however,marketswithasmallnumberofsellerswithmonopolypowersellingtoamarketwithfewbuyerswithmonopsonypowerismorecommon.TheSocialCostsofMonopsonyPower第81页/共100页Slide83MonopsonyPowerQuestionInthiscase,whatislikelytohappentoprice?TheSocialCostsofMonopsonyPower第82页/共100页Slide84LimitingMarketPower:

TheAntitrustLawsAntitrustLaws:PromoteacompetitiveeconomyRulesandregulationsdesignedtopromoteacompetitiveeconomyby:ProhibitingactionsthatrestrainorarelikelytorestraincompetitionRestrictingtheformsofmarketstructuresthatareallowable第83页/共100页Slide85ShermanAct(1890)Section1Prohibitscontracts,combinations,orconspiraciesinrestraintoftradeExplicitagreementtorestrictoutputorfixpricesImplicitcollusionthroughparallelconductLimitingMarketPower:

TheAntitrustLaws第84页/共100页Slide861983Sixcompaniesandsixexecutivesindictedforpriceofcoppertubing1996ArcherDanielsMidland(ADM)pleadedguiltytopricefixingforlysine--threesentencedtoprisonin1999LimitingMarketPower:

TheAntitrustLawsExamplesofIllegalCombinations第85页/共100页Slide871999RocheA.G.,BASFA.G.,Rhone-PoulencandTakedapleadedguiltytopricefixingofvitamins--finedmorethan$1billion.LimitingMarketPower:

TheAntitrustLawsExamplesofIllegalCombinations第86页/共100页Slide88ShermanAct(1890)Section2Makesitillegaltomonopolizeorattempttomonopolizeamarketandprohibitsconspiraciesthatresultinmonopolization.LimitingMarketPower:

TheAntitrustLaws第87页/共100页Slide89ClaytonAct(1914) 1) Makesitunlawfultorequireabuyer orlessornottobuyfroma competitor 2) ProhibitspredatorypricingLimitingMarketPower:

TheAntitrustLaws第88页/共100页Slide90ClaytonAct(1914) 3) Prohibitsmergersandacquisitionsif they“substantiallylessen competition”or“tendtocreatea monopoly”LimitingMarketPower:

TheAntitrustLaws第89页/共100页Slide91Robinson-PatmanAct(1936)ProhibitspricediscriminationifitislikelytoinjurethecompetitionLimitingMarketPower:

TheAntitrustLaws第90页/共100页Slide92FederalTradeCommissionAct(1914,amended1938,1973,1975) 1) CreatedtheFederalTrad