公司多元化經營外文文獻及文獻綜述畢業(yè)論文

本份文檔包含：關于該選題的外文文獻、文獻綜述一、外文文獻標題:Theeffectsofinstitutionalownershiponthevalueandriskofdiversifiedfirms作者:MohammadJafarinejada, SurendranathR.Joryb,ThanhN.Ngoc,期刊:InternationalReviewofFinancialAnalysis(Volume402015):207-219年份:2015TheeffectsofinstitutionalownershiponthevalueandriskofdiversifiedfirmsAbstractWestudythelinkbetweeninstitutionalownershipandfirms'diversificationstrategy,valueandrisk.OursampleincludesUS-listedfirmswithsegmentdatafrom1998to2012.Wefindthatnotallkindsofdiversificationarevalue-destroying;unlikeindustrially-diversifiedfirms,globalsingle-segmentfirmsaretradingatapremiumrelativetotheirimputedvalue.Thepresenceofinstitutionalinvestorsandthestabilityoftheirshareholdingspositivelyinfluencethelikelihoodthatafirmisdiversified.Theproportion(volatility)ofinstitutionalownershipishigher(lower)amongdiversifiedfirmscomparedtodomesticsingle-segmentfirms.Moreimportantly,thehighertheproportionsofinstitutionalshareholdings,thehighertheexcessvalueofthediversifiedfirmandthelowerthefirmidiosyncraticrisk.Institutionalownershipvolatility,ontheotherhand,isinverselyrelatedtoafirmexcessvaluebutpositivelyrelatedtoitsidiosyncraticrisk.Thus,thepresenceoflong-termstableinstitutionalinvestorsenhancesthevalueofdiversifiedfirms.Ourfindingsremainrobusttovariousmodelspecificationsandestimationtechniques.Keywords: Institutional ownership; Corporate diversification;Diversificationdiscount;IntroductionTheeffectofdiversificationonfirmvaluecontinuestoattractconsiderableresearchinterest.Therearetwomaintypesofdiversification:product-andgeographicdiversification(Vachani,1991andMartin,2008).Productdiversificationreferstothedegreetowhichfirmsareinvolvedindifferentindustries(werefertothemasbusinesssegments).Geographicdiversificationreferstotheextenttowhichfirmsareinvolvedindifferentcountries(werefertothemasgeographicsegments).Bodnar,Tang,andWeintrop(1997)findthatglobaldiversificationisassociatedwithhigherfirmvalue.Incontrast,Denis,Denis,andYost(2002)findthatdiversificationdecreasesfirmvalue.OtherstudiesthatsuggestthatdiversificationadverselyaffectsfirmvalueincludeBergerandOfek(1995),Fauver,Houston,andNaranjo(2004);andKimandMathur(2008).Corporatediversificationisappealingtoinvestors.Underthepremisethatcorporationsarebetteratdiversificationthanshareholders,corporatediversificationshouldlowershareholders'investmentriskatafractionofthecostincurredbyindividualinvestors(seeAgmonandLessard(1977);DoukasandTravlos(1988);HarrisandRavenscraft(1991);SandersandCarpenter(1998)).However,thediversityofoperationsatconglomeratefirmsmakesitharderforordinaryinvestorstomonitorthem(Fatemi,1984),openingthepossibilityformanagementtopursueself-interestobjectivesattheexpenseoftheshareholders(Palich,Cardinal,&Miller,2000).Suchagencyproblemswillreduceshareholders'returnoninvestmentincreasetheirrisk.Asaconsequence,ifthereisagroupouttherewhoisbetteratmonitoringmanagers,itisbettertofollowtheirlead.JensenandMeckling(1976),andShleiferandVishny(1986)suggestthatlargeinvestorscouldwellbethatgroup.Weproposetoconsiderthecontributiontofirmvalueandriskbroughtaboutbysuchanimportantgroupofinvestorsatdiversifiedfirms,i.e.,institutionalinvestors.Institutionalinvestors—includingmutualfunds,hedgefunds,pensionfunds,banksandinsurancecompanies—areleadingplayersinthefinancialmarketsaswellastheprimaryownersofUScorporateequity(Gillan&Starks,2000).EstimatesoftheirshareholdingsatUSfirmsrangefrom35%inthe1980sand60%inthe2000sto66%bytheendof2010.Giventhesizeoftheirequityinvestments,theytendtoexertconsiderablepressureonmanagementtocreatewealthforinvestors(seealso,ShleiferandVishny(1986)).JarrellandPoulsen(1987),Brickley,Lease,andSmith(1988);AgrawalandMandelker(1990)suggestadirectlinkbetweeninstitutionalinvestorsandshareholders'wealth.Consequently,managerspayalotofattentiontomeetthefinancialtargetssetbytheseinvestors(EasleyandO'hara,1987,Kyle,1985andClay,2002).Actionstakenbytheinvestorstendtogeneratealotofpressandmediaattention,especiallyatlargeanddiversifiedfirms.Manyinstitutionalinvestorsbelievethatdiversifiedfirmscangeneratemoreprofitbyrestructuringtheirdivisions;examplesincludecampaignsbyinvestorsdemandingrestructuringatbigfirmslikePepsiCo,Sony,Timken,andMcGraw-Hill.Doinstitutionalinvestors—aseffectivemonitorsoffirmperformance—supportdiversificationandaddvaluetodiversifiedfirmsbyvirtueoftheirpresence?Weattempttoanswerthequestionandanalyzetheimportanceoftwomeasuresofinstitutionalownershipondiversifiedfirms'valueandrisk,i.e.,theproportionofthesharesheldbytheinstitutionalinvestors(IOPr)andtheinstitutionalownershipvolatility(IOV).Thefirstmeasureisextensivelyusedintheliterature,thoughmostlyfocusedondomesticfirms.Anemergingliteratureontheeffectsofinstitutionalownershiponfirmvaluesuggeststhatinadditiontotheproportionofsharesheldbyinvestors,itisequallyimportanttoconsiderinstitutionalownershipstability.Theyarguethatnotallinstitutionalinvestorsstaywithafirmforthelong-term.Someareshort-termandwouldleaveatthefirstsignoftrouble.ElyasianiandJia(2010),andCallenandFang(2013)arguethatinstitutionalinvestorsaremoreincentivizedtomonitortargetfirmsandimproveshareholderwelfare.theextentthatdiversificationdestroysvaluewhileinstitutionalinvestorsaddvalue,wetestwhethertheirpresenceatdiversifiedfirmsaddsvalue.Wehypothesizethatdiversifiedfirmswithhigherproportionsofsharesheldbyinstitutionalinvestors(IOPr)andlowervariabilityintheproportions(IOV)areassociatedwithhigherexcessvalues.Similarly,wepositthatfirmriskisinverselyrelatedtoIOPrandpositivelyrelatedtoManagerswouldbeunderscrutinynottocripplethefirmwithnon-valueaddeddiversificationswhenmoresharesareheldbyinstitutionalinvestors(IOPr).Conversely,ifafirmpursuesthewrongtypeofdiversification,thenthereislittlereasonfortheinvestorstoholdontotheirshares.Thus,weshouldobserveahighervolatilityininstitutionalshareholdings(IOV)amongthissubgroupoffirms.WeexaminetheuniverseoffirmslistedinCOMPUSTATfrom1998to2012.WebreaktheuniverseofCOMPUSTATfirmsintofourgroups:(i)domesticsingle-segmentfirms(DS),(ii)domesticmulti-segmentfirms(DM),(iii)globalsingle-segmentfirms(GS)and(iv)globalmulti-segmentfirms(GM).Wefindthatunlikedomesticfirms,thetrendistogoglobal,i.e.,weobserveafallinthenumberofdomesticfirmsandariseinthenumberofglobalfirmsovertime.Wefindthatnotallkindsofdiversificationareassociatedwithnegativeexcessvalues.Asopposedtoindustrially-diversifiedfirms,globalsingle-segmentfirmstradeatapremiumrelativetotheirmatcheddomesticsingle-segmentfirms.Theidiosyncraticrisklevelsarelowerfordiversifiedfirmscomparedtodomesticsingle-segmentfirms.Theproportionofsharesheldbyinstitutionalinvestors(IOPr)ishigherandthevolatilityinthoseproportions(IOV)isloweratdiversifiedfirmscomparedtodomesticsingle-segmentfirms.Usingprobitregressions,wefindthatthelikelihoodtodiversifyispositivelyassociatedwiththeproportionofsharesheldbyinstitutionalinvestors(IOPr)andinverselyrelatedtoitsvolatility(IOV).UnivariateanalysessuggesttheexistenceofapositiverelationshipbetweenIOPrandfirm'sexcessvalueandaninverserelationshipbetweenIOPrandfirm'sidiosyncraticrisk.Conversely,isinverselyrelatedtoexcessvalueandpositivelyrelatedtoidiosyncraticrisk.Theevidencesuggeststhatthereexistsasignificantrelationshipbetweenthepresenceoflong-termstableinstitutionalinvestorsandtheabilityofdiversifiedfirmstocreatewealth.Consistentwiththeunivariatefindings,thecoefficientofIOPrispositiveandthatofisnegativeinpanelfixed-effectregressionsoffirms'excessvalues.ThecoefficientsofDMandGM,representingdomesticmulti-segmentfirmsandgloballydiversifiedmulti-segmentfirms,respectively,arebothnegativeandhighlysignificant.theotherhand,globalsinglesegment(GS)firmsareassociatedwithhigherexcessvalues.Inregressionsoffirms'idiosyncraticrisk,thecoefficientsofandIOPrarepositiveandnegative,respectively,suggestingthatfirmswithlowerproportionsofequityheldbyinstitutionalinvestorsandhighervolatilityinthatproportionareperceivedasriskierandcarryingmoreidiosyncraticrisk.Overall,theempiricalevidencesuggeststhatdiversifiedfirmvalueislinkedtoinvestorswithconsiderableandstableshareholdings.Furthermore,theabsenceofstable,long-terminstitutionalinvestorsincreasestheidiosyncraticriskofdiversifiedfirms.Ourempiricalfindingsarerobusttoalternativecontrolvariables,variousmodelspecificationsandestimationtechniques.Beyondcomplementingandextendingtheliteratureonthediversificationdiscount,thisstudyalsocontributestotheemergingliteratureontheroleofinstitutionalownershipstabilityonfirmgovernanceandperformance.thebestofourknowledge,ourstudyisthefirsttoassesstheimpactofinstitutionalownershipstabilityamongdiversifiedfirms.Weconsidertheeffectofinstitutionalinvestorsinlesseningthediversificationdiscount.Wealsoexaminethelinkbetweeninstitutionalinvestorsandfirmrisk.Theremainderofthepaperisorganizedasfollows.Section2reviewstheliteratureandformulatesthehypotheses.Section3presentsthedata.Section4presentsthemethodsused.WepresentanddiscussthefindingsinSection5,andconcludethepaperinthefinalsection.LiteraturereviewandhypothesesdevelopmentAtthefirmlevel,institutionalinvestorstendtoresistcounterproductivestrategieswhilesupportingbeneficialones,especiallyshareholderdrivenones(BethelandLiebeskind,1993,HillandSnell,1988,HoldernessandSheehan,1985andMikkelsonandRuback,1991).Theytendtolobbyseniorexecutivestoimplementrestructuringstrategiesthatarebeneficialtoalltheshareholders(seealsoBethelandLiebeskind(1993)).Attigetal.(2012)arguethatlong-terminstitutionalinvestorshavegreaterincentivesandefficiencies—economiesofscaleinthecollectionandprocessingofcorporateinformation—toengageineffectivemonitoring,whichinturnmitigatetheasymmetricinformationdilemmaandassociatedagencyproblems.Barclay,Holderness,andPontiff(1993)findthatinvestorsvaluetheskillsanddemandsofblockpurchasersandthatfirmvalueincreasesfollowingablocktrade.Theydocumentahighturnoverinmanagementfollowingthesetradesandadeclineinfirmvaluewhentheblockholderseitherfailtoachievecontrolfaceresistancefrommanagement.NavissiandNaiker(2006)findthatshareholdingbyactiveinstitutionalinvestorsofupto30%positivelyinfluencescorporatevalue.Beyond30%,theownershiptendstoreducefirmvalue,whichsuggeststhatthereexistsanon-linearrelationshipbetweenthetwo.Whentheseshareholdersbecometoolarge,thereexistsasignificantriskthattheywilljoinforceswithmanagementtosafeguardtheircommoninterestsattheexpenseoftheothershareholders,especiallyminority/individualones.Theauthorsfindthatpassiveinvestorsdonotaffectfirmvalue.Cornettetal.(2007)findthatthepercentagesofinstitutionalinvestorinvolvementinafirm,aswellastheirnumbers,areassociatedwithbetteroperatingcashflowreturns.However,thefindingsonlyholdwhentheinvestorshavenobusinessrelationwiththefirm;elsethereisnosignificantrelationshipbetweeninstitutionalinvestorsandfirmperformance.Intheory,aconglomeratefirmwithmultiplebusinesssegmentsshouldtradeatthesamepriceasthesumoftheindividualsegmentsasstandalonebusinesses.Yet,theliteraturefindsthatthisisrarelythecase.ThisinequalityisduetoasymmetricinformationandagencyconflictsalongthelinesexplainedbyMyers(1984);MyersandMajluf(1984).However,recentstudiesoninstitutionalownershipandstabilitysuggestthatinstitutionalinvestorscanhelpsolvesuchproblems.Westudywhethertheinvolvementofinstitutionalinvestorscanturnthefortunesofdiversifiedfirmsgiventheevidenceofadiversificationdiscount(Fauveretal.,2004,Jory&Ngo,2012).H1.Thereexistsapositiverelationshipbetweendiversifiedfirms'valueandtheproportionofthesharesheldbyinstitutionalinvestors.Nonetheless,notallinstitutionalinvestorsareequallymotivatedtoensurethelong-termwell-beingofafirm.Thereexistsomeinvestorswithaninterestinshort-termtrading,quickprofitsandturnaround.Theyarenotwillingtoincurlong-termmonitoringcostsandarenotinterestedinmonitoringfirm'smanagement.CallenandFang(2013)reviewsomescenariossuggestiveofashort-termbias.thefirstcase,thecostofmonitoringfarexceedsthecombinedcostsofsellingthesharesandinvestinginanothercompany.Second,manyinstitutionalinvestorsholdwell-diversifiedportfoliosthatdonotrequirethemtomonitoractivelyeverycompanyintheirportfolio.Third,thebenefitsofshort-termgainsfarexceedthoseoflong-terminvesting.Withtheirconstantbuyingandselling,theseinvestorscausealotofvariability/volatilityintheproportionofsharesheldbytheminthecompany.Thus,wehypothesizethatforvaluecreation,stableinstitutionalinvestorsaremoredesirablethantransientones.H2.Thereexistsaninverserelationshipbetweenfirmvalueandinstitutionalownershipvolatility.Institutionalinvestorstendtobelargeonesbuyingsignificantstakesinthecompaniestheyinvest.Giventhesizeoftheirinvestments,theypayparticularattentiontotherisk-takingactivityattargetfirms,andtheyhavesufficientinfluencetolobbyseniorexecutivestoswayrisk-takingdecisionsintheirfavor.Wehypothesizethatthepresenceoftheseinvestorswoulddissuademanagersfromtakingexcessiveidiosyncraticrisks—forinstance,engaginginunrelateddiversificationabroadwherethemanagershavelittleknowledgeof,thusincreasingtherisksthefirmfaces.Institutionalinvestorshavetheirownstakeholderstosatisfy—forinstance,pensionfundsandinsurancecompanieshavetomakeregularpaymentstotheirsubscribers—andtheywouldresistchangesthatwoulddisruptthoserelationships.theextentthattheirrequiredreturnoninvestmentislinkedtochangesinthevalueofthefirm,theywouldwithstandactionsthatwouldincreasethevarianceofthefirmreturnsandadverselyaffectitsabilitytopaydividend.Thiswouldalsobetrueforinstitutionalinvestorswhohaveselectedtargetsbasedontheircurrentbusinessstrategiesandaresatisfiedwiththestatusquo;thosewholacktheexpertiseincentivestomonitornewventuresandriskyundertakings;and,investorswhosewealthisconcentratedinthetargetcompany.Therearetwotypesofrisksfacedbyafirm,i.e.,marketandidiosyncraticrisks.Managementcanmoredirectlyaffectthelatter.Thus,forthepurposeofourstudy,weconsiderafirm'sidiosyncraticrisk.minimizeitsimpactonthevalueoftheirequityinvestment,wetestthehypothesisthatthepresenceofinstitutionalinvestorshelpstominimizeidiosyncraticrisk.H3.Thereexistsaninverserelationshipbetweenfirmidiosyncraticriskandtheproportionofsharesheldbyinstitutionalinvestors.Financialmarketscompriseinvestorsandtradersofdifferenttimehorizons(Malagon,Moreno,&Rodriguez,2015).Investorsengaginginfrequenttradingaremoreinterestedinshort-ratherthanlong-termgains.Theycouldlobbyformakeshiftcorporatechangesattheexpenseofchangesthatwouldhavebenefitedalltheshareholdersinthelongrun.Theirpresencewillalsodolittleinalleviatingtherisksassociatedwithmisalignmentofobjectives,opportunisticbehaviorandearningsmanagementattheinvesteefirmand,consequently,accentuatethefirm'sidiosyncraticrisk.Frequenttradinginthesharesofafirm—causedbyshort-termtraders—willleadtoanincreaseinthevolatilityoftheproportionsofsharesheldbyitsinvestors.Conversely,long-terminvestors—thosewhoaremorelikelytobuyandholdandcauselessvolatilityintheproportionsofsharesheldbyinvestors—aremoreincentivizedtomonitorfirmactivitiesandimproveshareholdervalue.Thus,wetestthehypothesisthatthereexistsapositiveassociationbetweenthevolatilityintheproportionsofsharesheldbyinvestorsandafirm'sidiosyncraticrisk.H4.Thereexistsapositiveassociationbetweenfirmidiosyncraticriskandinstitutionalownershipvolatility.DataOursampleoffirmsisfromtheCOMPUSTATdatabaseandoursampleperiodstartsin1998andendsin2012.WedefineadiversifiedfirmasonethatreportsdataontheindustrygeographicsegmentsintheCOMPUSTATsegmentdatatapes.SimilartoHe(2009),westartthesampleperiodin1998becausetheFinancialAccountingStandardsBoard(FASB)issuedSFAS131in1997,whichsignificantlyaffectsthewaybusinessesreportsegmentdata.Following,weexcludethefollowingfirmsfromoursample:(i)firmswithSICcodes(i.e.,utilityfirms)and(i.e.,financialfirms)sincetheyareheavilyregulated;(ii)firm-yearobservationswithsegmentsaleslessthan$20million;and(iii)firm-yearobservationswherethedifferencebetweenthetotalsalesofallitssegmentsandthereportedtotalsalesfortheentirefirmisgreaterthan1%.WefurtherobtainaccountingandfinancialdatafromCOMPUSTAT,ownershipdatafromThomsonFinancialandstockpricedatafromtheCenterforResearchinSecurityPrices(CRSP)databases.TheThomsonFinancialdatabasereportsinstitutional13Fcommonstockholdingsandtransactions.includescommonstockholdingsandtransactionsofinstitutionalmoneymanagerswhereholdingsofthemanagingcompany/filer'slevelareasperthe13Ffilingitself.ItcoversallNYSE,AMEX,NASDAQcommonstocksandincludesallmanagersfiling13FreportswiththeSEC.WepresentthesampledescriptivesinTable1.Webreakthesampleintofourgroupsasfollows:domesticsingle-segment(DS,i.e.,notdiversified),domesticmulti-segment(DM,i.e.,industriallydiversifiedonly),globalsingle-segment(GS,i.e.,geographicallydiversifiedonly)andglobalmulti-segment(GM,i.e.,bothindustriallyandgeographicallydiversified).Thetrendistowardmoregloballydiversifiedfirms;from18%in1998,theirproportionasapercentageoftheentiresampleincreasesto33%by2012.Wehave53,481firm-yearobservationsobtainedfrom11,882firmsdistributedasfollows,63%DS,12%DM,15%GSand10%GMfirms.MethodologyMeasuringexcessvalueexplorethevaluationconsequencesofdiversification,weusethesamemeasureofexcessvalueasinBergerandOfek(1995);andBodnaretal.(1997).Theexcessvalueoffirmiiscalculatedasthenaturallogoftheratioofthefirm'smarketvaluetoitsimputedvalue.Measuringidiosyncraticriskcompute a firm's idiosyncratic risk we use theFama and French,1992andFamaandFrench,1993modelandaddtheexcessreturnonaworldportfoliototheequationasfollows(seealsoStulz(1999)):ResultsProbitregressionsWemodelafirm'spropensitytodiversifyasafunctionofthecharacteristicsofthefirm,itsindustry,itsmacroeconomicenvironmentand,moreimportantly,theinstitutionalownershipvariablesofIOPrandTable2reportstheprobitestimatesfromtwodifferentmodels.Model(1)containstheIOPrvariablewhileModel(2)containsboththeIOPrandtheIOVvariables.valueofthecoefficientrepresentingthevariableIOPrispositiveandstatisticallysignificant.Conversely,thevalueofthecoefficientisnegativeandstatisticallysignificant.ThemarginaleffectsofIOPrandarepositiveandnegative,respectively.Thus,diversifiedfirmsareassociatedwithhigherproportionsofinstitutionalownershipandlowervolatilityinthatratioovertime.Wealsofindthattheoddsthatafirmisdiversifiedarepositivelyassociatedto:firmsize(ln(AT)),profitability(EBITS),beinglistedonamajorUSstockexchange(MAJOR),thenumberofdiversifiedfirmsintheindustry(NUMDIVF),theproportionofsalesgeneratedbydiversifiedfirms(PrINDS),andthenumberofM&Asoccurringintheindustry(NUMA).Conversely,capital-intensivefirms(CAPX),growthfirmsasmeasuredbytheQratio,aswellasgrowthindustries(INDUSTRYQ),growthinGDP(GDPGr)andtheindustry'sdollaramountofdeals(VOLMA)areinverselyrelatedtoafirm'spropensitytodiversify.ExcessvalueandidiosyncraticriskofdiversifiedfirmsWepresentthemeanandmedianexcessvaluesofindustrially-(i.e.,DM,GM)andgeographicallydiversified(i.e.,GS,GM)firmsinTable3.WecomparetheexcessvaluestothatofthesampleofDS(i.e.,domesticsingle-segment)firmsandvariousportfolioscomprisingDSfirms.MorepreciselyandfollowingVillalonga(2004),wecalculateeachfirm'spredictedprobabilitytodiversifyusingtheprobitmodelofEq.Foreachdiversifiedfirm,weformaportfoliocomprisingdomesticsingle-segmentfirmswithprobabilityvaluesfromthesamequartile.Sinceweruntwoversionsoftheprobitmodel,wepresentourfindingsbasedontwoportfoliosofmatcheddomesticsingle-segmentfirms(i.e.,portfolios1and2,respectively)foreverydiversifiedfirm.TheexcessvaluesofDM(meanof?8.20%inPanelA)andGM(meanof16.20%inPanelC)firmsaresignificantlylowerthanthecorrespondingvaluesofbothportfoliosofmatcheddomesticsingle-segmentfirms.Thus,industrialdiversificationisassociatedwithlowerexcessvalues.Conversely,theexcessvaluesofglobalsinglesegmentfirms(GSfirmsinPanelB)arepositiveandsignificantlyhigherthanthoseofdomesticsingle-segmentfirms.OurfindingsareconsistentwithDenisetal.(2002),KimandMathur(2008);andJoryandNgo(2012).Wealsocomparetheidiosyncraticrisksofthefourgroupsoffirms.Theidiosyncraticriskmeasuresofthediversifiedfirms(i.e,DM,GSandGMfirms)areallsignificantlylowercomparedtoeitherthesampleofdomesticsingle-segmentfirmsormatchingportfoliosofdomesticsingle-segmentfirms.Thecombinationofdifferentbusinessgeographicunitsleadstoaportfolioeffectthatdampenstheindividualriskofeachunitcausingadiversifiedfirmtoreportlowerriskmeasures.Thepercentageofsharesownedbyinstitutionalshareholders(IOPr)andthevolatilityofinstitutionalownership(IOV)WepresentthevaluesofandbydiversificationtypeinTable4.WecomparethefigureswithvarioussubsamplesofDMfirms.ThemeanandmedianIOPrfiguresare21%and7%,respectivelyfordomesticsingle-segmentfirms,i.e.,non-diversifiedfirms.contrast,theproportionofcompanysharesheldbyinstitutionalinvestorsishigheramongdiversifiedfirms(bothindustrially-andgeographically-diversifiedfirms).Forinstance,themeanvaluesofIOPratDM,GSandGMfirmsare39%,52%and56%,respectively.Thecorrespondingmedianfiguresare38%,57%and64%,respectively.Thus,institutionalinvestorsholdahigherproportionofthesharesatdiversifiedfirmswhencomparedtonon-diversifiedones.6ConclusionWhilesingle-segmentdomesticfirmsstilldominatethecorporatelandscape,weobserveagradualdeclineintheirnumbersandanincreaseinthefrequencyofglobally-diversifiedfirms.Wefindthatnotallkindsofdiversificationarevalue-destroyingandthatglobalsingle-segmentfirmstradeatapremiumcomparedtomatcheddomesticsingle-segmentfirms.Industrially-diversifiedfirmsthough(eitherdomesticorglobal)areassociatedwithlowerexcessvalues.Nonetheless,thecombinationofthedifferentbusinessgeographicunitsexertsaportfolioeffectthatcausestheoverallenterpriserisktodeclinecausingdiversifiedfirmstoreportlowerriskmeasurescomparedtodomesticsingle-segmentfirms.Weprovideempiricalevidencethatinstitutionalownershipisacorevaluedriverofdiversifiedfirms.Theyareassociatedwithhigherlevelsofinstitutionalshareholdingsandmorestableshareholdingsovertime.Theproportionandstabilityofinstitutionalownershiparepositivelyrelatedtofirmvalueandinverselyrelatedtoitsidiosyncraticrisk.Ourresultsindicatethatthepresenceoflong-termstableinstitutionalinvestorsisasourceofvaluefordiversifiedcorporations.二、文獻綜述公司多元化經營文獻綜述摘要公司多元化經營的相關問題是近年來公司戰(zhàn)略管理、產業(yè)經濟學和公司金融領域的一個研究熱點，也是一個在理論界頗具爭議的話題。國內外學者對此進行了大量的理論和實證研究，但至今未得出一致的結論。本文就國內外關于多元化經營與企業(yè)績效的理論和實證研究成果進行綜述，以期為該領域的進一步研究提供有益的線索。關鍵詞：多元化經營；企業(yè)績效；文獻綜述1引言對于多元化經營的研究最早起源于西方國家，美國學者H.I.Ansoff在20世紀50年代首次提出“多元化經營”這一概念，隨后世界各國的研究學者們開始廣泛關注。到了60年代，多元化經營開始走向頂峰，西方國家出現(xiàn)的混合并購浪潮推動著多元化經營迅猛發(fā)展，但這種發(fā)展趨勢并未持續(xù)太長時間，隨著許多實施多元化經營的企業(yè)出現(xiàn)資源分配不合理等問題，企業(yè)的經營狀況日益惡化，企業(yè)開始考慮是否應該繼續(xù)選擇這一經營戰(zhàn)略。自此以后，企業(yè)逐漸轉向“歸核化經營”。我國企業(yè)實施多元化經營戰(zhàn)略較西方國家起步晚，我國市場經濟的不斷完善、改革開放的進一步推動才逐漸使企業(yè)對多元化經營感興趣。我國企業(yè)真正開始關注多元化經營問題是在20世紀90年代初期，而今多元化經營在我國企業(yè)的戰(zhàn)略選擇中越來越占據(jù)重要地位，當然，我國企業(yè)在實施多元化經營的過程中也出現(xiàn)了大量經營失敗的情況。但是我國的多元化進程不同于西方國家，大多數(shù)企業(yè)仍繼續(xù)堅持以多元化經營為主要的發(fā)展戰(zhàn)略。我國學術界對于多元化經營的實證研究時間不長，在已有的相關文獻中大多數(shù)側重于對“多元化經營與企業(yè)績效的關系”的實證檢驗，且得到的研究結果并不一致。目前國內學者對多元化經營的研究方法仍有不足，更缺乏較深層次地研究。2國外的研究學術界對多元化與企業(yè)績效進行的研究主要包括多元化程度與績效、多元化類型與績效、代理成本與企業(yè)績效三個方面。2.1多元化程度與績效.多元化程度與績效研究者們使用了不同的多元化程度的衡量指標和績效衡量指標，得出了不一致的研究結論。Gort(1962)第一個研究了多元化企業(yè)的獲利性。他通過企業(yè)的業(yè)務單元數(shù)量、專業(yè)化比率以及業(yè)務單元數(shù)量和專業(yè)化比率的乘積這三種計量指標來衡量多元化的程度，分析了1947年～1957年美國111家大公司的情況。其結果表明企業(yè)多元化與投資報酬率之間基本不存在相關性。Raverscraft(1983)以1975年的258家公司為樣本，用Herfindahl指數(shù)計量多元化程度，結果表明企業(yè)多元化程度與邊際毛利率之間不存在顯著的相關性。多數(shù)實證研究表明多元化程度的增加會降低企業(yè)績效。Langz(1994)利用Compustat數(shù)據(jù)庫提供的數(shù)據(jù)分析了多元化對TobinQ值的影響，結果發(fā)現(xiàn)Q值與公司多元化之間呈負相關關系。Be