日本政府自1996年實施金融大改革(Big Bang)，金融市場從保守走向自由開放，面對競爭越趨激烈的環境，日本產險業開始出現公司併購重組的情形，使得市場越趨集中。無論是市場結構的改變，或是併購亦可能對公司既行營運模式造成改變，進而影響公司的經營效率，都可能對公司的市場壟斷力造成影響，進而影響市場的競爭度。本研究以2001-2012年日本產險市場為研究對象，主要目的在探討市場集中度及公司效率此兩種變數是否會對競爭度產生影響。實證模型採用追蹤資料固定效果模型作分析，並以Lerner指數作為衡量公司市場壟斷力的變數，赫芬達指數作為衡量市場集中度變數，以資料包絡分析法所求出之效率值代表效率變數。實證結果發現，市場集中度對於公司的市場壟斷力無顯著影響，而產險公司效率與公司的壟斷力呈正向關係，當公司效率越高，其壟斷力越高，而市場競爭程度越低。 / Since the Japanese financial system reform, “Big Bang,” was commenced in 1996, the financial market in Japan has been transformed into free and open market. At the same time, the Japanese insurance market became more competitive due to the regulatory changes. Many mergers and acquisitions appeared in Japanese insurance industry and that increased the market concentration. The reform has also changed firm operation modes and then have impact on firm efficiency. Furthermore, the changes of market structure and firm efficiency may have impact on market power and therefore affect the level of competition. The objective of this study is to assess the impact of concentration and efficiency on competition in Japanese property-liability insurance industry using the fixed effect model. The research period is from 2001 to 2012. This study utilizes Lerner index to measure market power (competition) and Herfindahl-Hirschman index (HHI) to measure market concentration. And the data envelopment analysis (DEA) method is applied to evaluate the efficiency of insurance companies. The results show that the relation between concentration and competition is not significant. This paper also finds evidence that higher firm efficiency leads to higher market power (lower competition).

我國自1990年實施金融自由化以來，「銀行過多」(over-banking) 現象逐漸浮現，銀行業的過度競爭與1997年發生的亞洲金融風暴，促使政府推動金融改革政策，試圖藉銀行間的合併提高銀行業者的競爭力與經營績效，提升國際競爭力並邁向國際化。過去已有相當多文獻從事銀行業競爭程度的研究，大致分成結構法與非結構法兩類，其中不乏以非結構法之PR (Panzer and Rosse, 1987) 檢定法，對包括台灣在內的銀行業競爭程度進行探討，但較少以事前模擬的方式，分析銀行間相互合併後對市場競爭程度的影響。本研究針對我國1997-2009年銀行業資料，運用PR檢定法模擬合併前後銀行業的市場競爭程度，附帶分析其對規模、範疇經濟與技術效率之影響。發現當合併的家數愈多，銀行壟斷力及技術效率分數皆會愈高；銀行的合併對規模經濟的增加則有其極限，每兩家合併的情況下最具規模經濟，但隨合併的家數增加時規模經濟有降低之傾向；不論合併的家數為何，範疇經濟皆存在。

本研究以日本國內產物保險公司作為研究對象，研究期間為1986年至2010年，共25個年度。本研究應用固定效果之GMM（一般化動差法）模型，以Lerner index衡量市場獨占力（競爭度），檢驗對日本產險公司之市場獨占力（競爭度）對於公司的財務穩定度以及各種風險之影響，包括總風險、核保風險以及投資風險。本研究發現日本國內產險公司獨占力與各風險大多存在負相關：越高獨占力（越低競爭度）的公司其總風險及核保風險越低。然而，越高獨占力（越低競爭度）的公司容易面對越高的投資風險。本研究結果亦顯示，獨占力對於風險之影響於1997至2010之研究期間有顯著效果，惟其於1986至1996之研究期間效果不顯著。 / This paper chooses Japanese domestic general insurance company as the objective and the research period is from 1986 to 2010, 25 sample years in total. We apply fixed-effect in the GMM (Generalized method of moments) to examine the impact of the market power (Lerner index) specifically in insurance market on financial stability and different risks of insurance company, including total risk, underwriting risk and investment risk. The result suggests in general, negative relation exist between market power and risks in Japanese domestic general insurance industry: We find that the higher the market power (the lower competition), the lower the total risk and underwriting risk. On the other hand, higher marker power (lower competition) leads to higher investment risk. Our finding also shows that market power has an impact in the period 1997-2010 but not for the period of 1986-1996, which confirms that Japanese financial reform in 1996 might have influence on risks and financial stability.