【正文】 實(shí)力懸殊的寡頭的行為時(shí)卻不夠現(xiàn)實(shí)。以此類推 。這種環(huán)境下，企業(yè)經(jīng)理人的決策具有以下特點(diǎn)： 經(jīng)理們知道自己的決策會(huì)影響到對(duì)手的銷售情況和利潤水平 經(jīng)理們做出決策后，對(duì)手會(huì)對(duì)這些決策作出反應(yīng) 經(jīng)理們的銷售和利潤狀況依賴于對(duì)手的反應(yīng) 但是，經(jīng)理們并不確知對(duì)手實(shí)際上將如何反應(yīng) 在這種環(huán)境下，經(jīng)理人的成功在于學(xué)會(huì)如何預(yù)期市場中其它競爭對(duì)手的行動(dòng)和反應(yīng)，從而作出利潤最大化的決策 寡頭的管理決策 ? 定義 某一產(chǎn)業(yè)只存在少數(shù)幾個(gè)賣者（通常少于 10個(gè)）的市場組織形式。 – You are a monopolistically petitive firm and the inverse demand for your brand is P = 100 Q Marginal Cost ? C(Q) = 125 + 4Q2, ? So MC = 8Q ? This is independent of market structure Price Taker ? MR = P = $40 ? Set MR = MC ? 40 = 8Q ? Q = 5 units ? Cost of producing 5 units ? C(Q) = 125 + 4Q2 = 125 + 100 = 225 ? Revenues: ? PQ = (40)(5) = 200 ? Maximum profits of $25 ? Implications: Expect exit in the longrun Monopoly/Monopolistic Competition ? MR = 100 2Q (since P = 100 Q) ? Set MR = MC, or 100 2Q = 8Q – Optimal output: Q = 10 – Optimal price: P = 100 (10) = 90 – Maximal profits: ? PQ C(Q) = (90)(10) (125 + 4(100)) = 375 ? Implications – Monopolist will not face entry (unless patent or other entry barriers are eliminated) – Monopolistically petitive firm should expect other firms to clone, so profits will decline over time 寡頭壟斷 Oligopoly ? 在完全競爭、完全壟斷、壟斷競爭三種市場環(huán)境中，企業(yè)決策始終遵循著 SCP邏輯：即市場結(jié)構(gòu)決定企業(yè)行為和企業(yè)績效 Market Structure – Number of firms, size, etc. Conduct – Pricing, advertising, RD, etc. Performance – Profitability, consumer surplus, social welfare. ? 而在有些市場環(huán)境下，企業(yè)決策機(jī)制似乎難以固定描述。 該公司經(jīng)理估計(jì)該企業(yè)面臨的需求方程為 p = , 而該公司的長期總成本函數(shù)為 : TC = 400Q 20Q2 +Q3 問： 該公司的長期均衡價(jià)格和產(chǎn)量各是多少？它將獲得多少利潤？此時(shí)，壟斷競爭的長期均衡條件是否得到滿足？ 壟斷競爭企業(yè)前景如何 ? 如何延遲零經(jīng)濟(jì)利潤的最終結(jié)局？ parison Maximizing Profits: A Synthesizing Example ? C(Q) = 125 + 4Q2 ? Determine the profitmaximizing output and price, and discuss its implications, if – You are a price taker and other firms charge $40 per unit。 D0 D1 $ AC MC D MR Q* P* Quantity of Brand X MR1 D1 Entry P1 Q1 Long Run Equilibrium (P = AC, so zero profits) Graphically 壟斷競爭下的長期均衡 （續(xù)） D q 0 pE LMC LAC E P,C,R qE MR （ 1）由于廠商可以自由進(jìn)入，壟斷競爭長期均衡滿足： LAC=AR=P， MC=MR （ 2）壟斷競爭的效率低于完全競爭（均衡價(jià)格高、均衡產(chǎn)量低），因?yàn)榫鈺r(shí) p≠M(fèi)C, 同時(shí)生產(chǎn)沒有推進(jìn)到平均成本最低點(diǎn) （ 3）壟斷競爭的效率高于完全壟斷 （ 4）壟斷競爭帶來了產(chǎn)品差異化，更好地滿足了消費(fèi)者；同時(shí)有利于技術(shù)進(jìn)步 Monopolistic Competition The Good (To Consumers) – Product Variety The Bad (To Society) – P MC – Excess capacity ? Unexploited economies of scale The Ugly (To Managers) – Zero Profits 壟斷競爭的決策舉例 “ DogsGoneAway（狗去矣）”公司是芝加哥專門為寵物提供葬禮服務(wù)的公司。否則廠商停產(chǎn) MR Long Run Adjustments? ? In the absence of free entry, no adjustments occur. ? If the industry is truly monopolistically petitive, there is free entry. – In this case other “ greedy capitalists” enter, and their new brands steal market share. – This reduces the demand for your product until profits are ultimately zero. 壟斷競爭下的長期均衡 D q 0 pE LMC LAC E P,C,R qE MR 只要存在短期超額利潤，就有投資者進(jìn)入；隨著新企業(yè)的進(jìn)入， 替代品數(shù)量將增加，代表性企業(yè)面臨的需求曲線將向左下方移動(dòng)。 firms have limited market power. 與完全壟斷類似 ? Free entry and exit, so firms will earn zero profits in the long run. 與完全競爭類似 Managing a Monopolistically Competitive Firm ? Market power permits you to price above marginal cost, just like a monopolist. ? How much you sell depends on the price you set, just like a monopolist. But … ? The presence of other brands in the market makes the demand for your brand more elastic than if you were a monopolist. ? You have limited market power. 壟斷競爭下的短期均衡 D q 0 pE mrE SMC SAC E dE P,C,R qE 短期均衡滿足： AR=AVC。 此時(shí)，企業(yè)具有非常強(qiáng)的“市場力” 在不失去全部市場（份額）的前提下提價(jià)的能力 ? 壟斷市場的特征 ? 相關(guān)市場上只有一家公司 ? 大多數(shù)壟斷者都是“本土的” ? 企業(yè)的產(chǎn)品需求線即市場需求曲線 ? 企業(yè)可以控制市場價(jià)格 – 但價(jià)格又會(huì)影響到對(duì)壟斷者產(chǎn)品的需求 完全壟斷存在的原因 （ 1）規(guī)模經(jīng)濟(jì)與自然壟斷 在規(guī)模報(bào)酬遞增行業(yè)（一家經(jīng)營比兩家經(jīng)營有利）特別明顯，如鐵路業(yè)、城市供水供電，初期投資成本構(gòu)成了進(jìn)入壁壘 （ 2）原材料控制與專用資產(chǎn) 如二戰(zhàn)以前的美國制鋁公司，壟斷了鋁土礦的開采；石油管道；資金市場 （ 3）法規(guī)壁壘（如專利權(quán)、特許經(jīng)營） 公共郵政、有線電視、廣播等 （ 4）剩余生產(chǎn)能力 （ 5）品牌效應(yīng)（如經(jīng)驗(yàn)產(chǎn)品）和網(wǎng)絡(luò)外延（如移動(dòng)和聯(lián)通）等 可以細(xì)分為三類原因 “ Natural” Sources of Monopoly Power ? Economies of scale ? Economies of scope ? Cost plementarities “ Created” Sources of Monopoly Power ? Patents and other legal barriers (like licenses) ? Tying contracts ? Exclusive contracts ? Collusion Contract... I. II. III. Legal Barriers to Monopoly Power ? Section 3 of the Clayton Act (1914) – Prohibits exclusive dealing and tying arrangements where the effect may be to “ substantially lessen petition” ? Sections 1 and 2 of the Sherman Act (1890) – Prohibits pricefixing, market sharing, and other collusive practices designed to “ monopolize, or attempt to monopolize” a market Managing a Monopoly ? Market power permits you to price above MC ? Is the sky the limit? ? No. How much you sell depends on the price you set! A Monopolist’ s Marginal Revenue P Q Q Demand Elastic Inelastic Unitary MR Total Revenue ($) 完全壟斷下的短期均衡 ? 壟斷廠商面臨的需求和邊際收益 方便起見，假設(shè)市場需求是線性的 ? 壟斷廠商的短期均衡條件 ARAVC。所以短期行業(yè)供給曲線往往向右上傾斜。直到 p=LAC=LMC（最大化利潤為 0） 企業(yè)才會(huì)停止進(jìn)出，行業(yè)達(dá)到 長期穩(wěn)定的均衡 小 結(jié) ? 短期利潤引發(fā)“進(jìn)入” ? “進(jìn)入”增加了市場供給，推動(dòng)市場價(jià)格下降和市場供應(yīng)上升 ? 單個(gè)企業(yè)的產(chǎn)品需求曲線向下移動(dòng) ? 企業(yè)將減少產(chǎn)出以便最大化利潤 ? 通過企業(yè)進(jìn)出行業(yè)的行為，市場可以調(diào)節(jié)產(chǎn)出使P=LMC=LAC，也就是