Researchers in various business disciplines use the event study methodology to assess the market value of firms through capital market reaction to news in the public media about the firm's activities. Capital market reaction is assessed based on cumulative abnormal return (sum of abnormal returns over the event window). In this study, the event study methodology is used to assess the impact that two important information technology activities, Internet security breach and ecommerce initiative, have on the market value of firms. While prior research on the relationship between these business activities and cumulative abnormal return involved the use of regression analysis, in this study, we use decision tree induction and regression.For the Internet security breach study, we use negative cumulative abnormal return as a surrogate for damage to the breached firm. In contrast to what has been reported in the research literature, our results suggest that the relationship between cumulative abnormal return and the independent variables for both the Internet security breach and ecommerce initiative studies is complex, often involving conditional interactions between the independent variables. We report that the incomplete contract theory is unable to effectively explain the relationship between cumulative abnormal return and the organizational variables. Other ecommerce theories provide support to the findings from our analysis. We show that both attack and firm characteristics are determinants of damage to breached firms.Our results revealed that the use of decision tree induction presents additional insight to that provided by regression models. We illustrate that there is value in using data mining techniques to study the market value of e-commerce initiative and Internet security breach and that this approach has applicability in other domains and that Decision Tree can enhance the event study methodology.We demonstrate that Decision Tree induction can be used for both theory building and theory testing. We specifically employ Decision Tree induction to test and enhance ecommerce theories and develop a theoretical model for cumulative abnormal return and ecommerce. We also present theoretical models for Internet security breach and damage to the breached firm. These models can be used by decision makers in Internet security and ecommerce investments strategic formulations and implementations.

This dissertation consists of three studies on the anticipation of mergers and acquisitions (M&amp;As) and its impact on takeover event studies.  Article I investigates whether the market can anticipate both takeovers and their payment forms prior to their announcement dates. This article also proposes a new time-series approach for detecting the ex-ante deal-anticipation and payment-form anticipation dates. The results indicate that the majority of deals and their payment forms are anticipated much earlier than has been documented in previous takeover studies. Moreover, controlling for the anticipation dates matters for explaining the choice of payment method in M&amp;As. Article II studies how assuming that M&amp;As are unpredictable during the estimation window affects the measurement of abnormal returns. The results show that a part of takeover synergy is indeed incorporated into the stock prices during the estimation window of previous studies, around the deal-anticipation dates. This article estimates the parameters of the expected return model from the pre-anticipation period to control the consequences of ex-ante anticipation on the estimates of abnormal returns. Using the anticipation-adjusted approach significantly improves the estimation of the event-window abnormal returns, and provides new insights into some well-documented takeover results. Article III examines how the abnormal returns are affected when a standard event study assumes that the parameters of the expected return model are stable. Using a sample of firm takeovers, the results indicate that the parameters are indeed unstable. This article introduces a time-varying market model to account for the dynamics of merging likelihood when it estimates the abnormal returns. The findings show that the stability assumption causes a standard event study to overestimate significantly the abnormal returns to the target and acquirer shareholders. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 3: Manuscript.</p>

[pt] O papel deste estudo foi investigar se as alterações de ratings de países da América Latina produzem impactos significativos no mercado acionário brasileiro. Por ser tratar de teste de hipótese semiforte de eficiência de mercado, o estudo foi conduzido através de teste estatístico paramétrico. Os resultados encontrados corroboram com hipótese de efeito contágio no mercado acionário brasileiro, através do índice IBX. O estudo também conclui que a intensidade do impacto também depende do tipo de informação incorporada nos anúncios de mudanças de classificações soberanas. / [en] The objective of this study was to investigate if sovereign rating changes for Latin America affect the Brazilian stock market. To measure this potential impact, the parametrical statistical test of event study was adopted, commonly used in semi-strong market efficiency tests. The results support the idea of contagion effects in the Brazilian Market through the IBX index. This study also concludes that the impact depends on the type of announcement of ratings changes.

Denna studie undersöker huruvida den faktiska avkastningen för ett flygbolags aktie skiljer sig från den förväntade avkastningen i samband med att ett av flygbolagets plan kraschar. För att undersöka förekomsten av abnormal avkastning genomförs en eventstudie där 71 flygplanskrascher mellan åren 1980 till och med 2018 undersöks. Resultatet visar att det förekommer en genomsnittlig kumulativ avvikelseavkastning på -4,65% dagen då kraschen sker inklusive nästkommande dag, vilken är statistiskt signifikant på 1%. Vidare har antalet dödsfall som en flygplanskrasch orsakar en statistiskt signifikant påverkan på sambandet med styrkan 1%, där fler dödsfall resulterar i en större negativ kumulativ abnormal avkastning.

This study aims to investigate if an outside investor can gain positive return from investing in company stocks on the Swedish stock market following published announcements of insider stock purchases done through the Swedish financial regulatory authority Finansinspektionen’s public insider transaction registry. Studying a total of 5 966 announced stock purchases during the period 2014 – 2018, the study finds significant positive abnormal return over all studied time periods following the announcement date, regardless of differences in company size. Highest return was found in smaller companies, at the cost of accepting a higher degree of risk. Despite significant results showing informational value of the announced purchases, economic gain from following insider behavior could be inhibited by the cost of investment and would require the outside investor to pick the right stock, which could prove difficult.

[pt] A introdução do modelo regulador deve ser capaz de calibrar o trade off entre os interesses do consumidor e dos investidores privados, em busca de uma performance adequada para o setor, aumentando eficiência, gerando volumes agregados de investimentos para sustentar o crescimento de longo prazo. A revisão do modelo de atuação do Estado no setor de telecomunicações brasileiro e a forma como foi implementada pôde ser considerado um caso de sucesso em nível internacional, evidenciado pelos mais de 100 bilhões de reais investidos, ampliação da oferta de produtos e serviços, melhoria da qualidade do serviço e pela projeção do país no cenário das telecomunicações mundial. No entanto, desde o início do governo atual, os constantes desentendimentos entre o Ministério das Comunicações e a ANATEL trouxeram um ambiente de instabilidade para o setor. A partir de fevereiro de 2003 iniciou-se por parte do Executivo uma forte discussão sobre os contratos, críticas à atuação da agência reguladora em geral e, em particular, aos aumentos das tarifas de telefonia. Nesta época o governo cogitou a substituição do IGP-DI como indexador das tarifas de telefonia fixa. O objetivo desta dissertação é, a partir da disputa travada entre Executivo, ANATEL e empresas fixas na definição dos índices de reajuste das tarifas fixas no ano de 2003, verificar se este episódio trouxe reflexos nos retornos das ações mais líquidas destas empresas na Bolsa de Valores de São Paulo. A metodologia de estudo de eventos foi escolhida para a condução deste trabalho, método amplamente utilizado em Finanças em função de sua forte aplicabilidade geral. Adicionalmente, foi aplicada a metodologia proposta por Izan (1978), objetivando fazer face à dificuldade adicional trazida pelo fato de tratar-se de um evento relacionado a regulação. / [en] The introduction of any regulatory model must be able to balance the trade off that exists between consumer and investors interest, aiming an adequate performance for the sector, increasing efficiency and generating volumes of investments enough to sustain long term growth in the economy. The regulatory reform in Brazilian Telecommunication sector can be considered a case of success internationally, which can be seen due to more than 100 billion of reais invested since then, the availability of products and services, quality improvements, and due to the relevance Brazil assumed in the international telecommunication scenario. However, since the beginning of the current Government, constant disagreements between the Telecommunication Ministry and ANATEL brought an instable environment to the sector. Since February 2003 it started strong discussions regarding contracts, criticism to the way the regulatory agency used to act as a whole and, particularly, the fixed telecoms tariffs readjustments. At that time, the Government considered the substitution of IGP-DI as the index for fixed telecoms readjustments. The objective of this study is, in light of the dispute between Government, ANATEL and fixed telecom companies in 2003, to investigate if this episode brought any impacts to the return of the most liquid shares of fixed telecom companies at the São Paulo Stock Exchange. The Event Study Methodology was chosen to proceed with this study, which is widely used in Finance due to its strong general applicability. Additionally, it was used the methodology proposed by Izan (1978), aiming to address the additional difficulty brought by the fact that this is a regulatory event.

Made available in DSpace on 2016-04-25T16:44:31Z (GMT). No. of bitstreams: 1 Katia Teresinha Guerra Gomes.pdf: 888955 bytes, checksum: 4cb2854de9af35ae524beb29184c9874 (MD5) Previous issue date: 2012-10-22 / This dissertation aims at the study of 22 companies of the international insurance segment in order to ascertain whether insurers already consider in the price of its shares the expectations of future crises and also analyze which insurance market is more efficient. To this purpose, this work studied and presented results on the following aspects: a study of 20 companies of highest market value of the international insurance segment, verifying the performance of rolling stock of each comparing with the market index of the stock exchange on which the action is negotiated. Additionally, conducted an analysis between the Brazilian insurance markets and other markets studied in the sample, verifying if the insurance segment in Brazil presents itself more efficient than international markets surveyed; and third, and last, an analysis of the stock indexes out of reshaping crisis moments as selected sample. For this survey, the methodology which has been used was the study of events. According to the results observed in this work and except that the findings are limited to the sample observed, the results indicate the occurrence of the generation of statistically significant abnormal returns after the announcement of the crisis. For the windows immediately before and after the event window, was not observed to generate statistically significant abnormal returns. Thus, we accepted the null hypothesis, assuming indications anticipated adjustments, resulting from an accumulation of factors. The results comparison among companies of the 4 sub samples showed the absence of a default behavior for the series as a whole. And considering that economic crises are the result of continuous systemic adverse events, with the results published in the media, it is reasonable to accept that the prices gradually adjusted before the measurement point / A presente dissertação tem por objetivo o estudo do retorno das ações ordinárias de 22 empresas do segmento de seguros internacional a fim de verificar se elas já embutiram no preço de suas ações as expectativas de crises futuras e também analisar qual mercado segurador se apresenta mais eficiente. Para tanto, este trabalho estudou e apresentou resultados sobre os seguintes aspectos: um estudo das 20 empresas de maior Valor de Mercado que compõem o segmento de seguros internacional, verificando o desempenho evolutivo das ações de cada uma delas comparando com o índice de mercado da Bolsa de Valores na qual a ação é negociada. Adicionalmente, efetuou-se uma análise entre o mercado segurador brasileiro e os demais mercados estudados na amostra, verificando se o segmento de seguros no Brasil se apresenta mais eficiente que os mercados internacionais pesquisados; e em terceiro e último, uma análise dos índices bursáteis nos momentos das crises financeiras selecionadas como amostra. Para tal pesquisa, utilizou-se da metodologia de estudo de eventos. De acordo com os resultados observados nesse trabalho e ressalvado que as conclusões se limitam à amostra observada, conclui-se que os resultados evidenciaram a ocorrência da geração de retornos anormais estatisticamente significativos, após o anúncio da crise. Para as janelas imediatamente anteriores e posteriores a janela do evento, não foi observada a geração de retornos anormais estatisticamente significativos. Com isso, aceitou-se a hipótese nula, assumindo indícios de ajustes antecipados, resultantes de um acumulo de fatores. A comparação dos resultados entre as empresas das 4 sub amostras evidenciaram a inexistência de um comportamento padrão para a série como um todo. E ainda considerando que as crises econômicas são resultantes de uma continuidade de eventos sistêmicos adversos, com seus resultados divulgados na mídia, é admissível aceitar que os preços gradualmente se ajustaram antes do ponto de medição

Made available in DSpace on 2016-03-15T19:25:48Z (GMT). No. of bitstreams: 1 Luis Estebao de Oliveira Neto.pdf: 1669457 bytes, checksum: 963666a8cfdfb2d10671cf8f29c0d6f8 (MD5) Previous issue date: 2007-03-07 / Fundo Mackenzie de Pesquisa / In the past few years, strategic alliances have been more and more used as alternatives to the vertical integration of companies. Continuing a line of investigation that began in the middle of the eighties with the classic article written by McConnell e Nantell (1985), the purpose of this essay is to evaluate the impact of announcements of strategic alliances formations, in all their many forms, over the stock prices of the companies participating in the alliances. From a sample formed by 147 announcements of strategic alliances formations, published from 1996 to 2006, involving 48 companies from different areas, an event study was developed based on the Market Efficiency Hypothesis s theory, as postulated by Fama (1970). The results obtained from the total sample suggest that the Brazilian s capital market reacts positively to announcements of strategic alliances formations, and in a very consistent way with the market efficiency s hypotheses, presenting statistically significant results considering an event window of two days length. The results obtained from the sample segmentations also suggest significant indications that investors perceive joint ventures as a type of association that have a higher potential to aggregate value to companies, when compared to other forms of alliances. / Nos anos recentes, as alianças estratégicas têm sido cada vez mais utilizadas como alternativas à integração vertical das empresas. Dando continuidade a uma linha de investigação que teve início em meados da década de 1980 com o artigo clássico de McConnell e Nantell (1985), este trabalho tem por objetivo avaliar o impacto dos anúncios de formação de alianças estratégicas, em todas as suas diversas formas, sobre os preços das ações das empresas participantes das alianças. A partir de uma amostra constituída por 147 anúncios de formação de alianças estratégicas, publicados no período de 1996 a 2006, envolvendo 48 empresas de diferentes setores, desenvolveu-se estudo de evento apoiado no eixo teórico da Hipótese da Eficiência de Mercado, postulada por Fama (1970). Os resultados obtidos a partir da amostra total sugerem que o mercado brasileiro de capitais reage positivamente a anúncios de formação de alianças e de maneira bastante consistente com a suposição de eficiência de mercado, apresentando resultados estatisticamente significantes para uma janela do evento de dois dias. Os resultados obtidos a partir das segmentações da amostra também sugerem significativos indícios de que as joint ventures são percebidas pelos investidores como formas de associação que possuem maior potencial de agregação de valor para as empresas, quando comparadas às outras formas de alianças.

This study employs event study to show that, on average, exchange switching in Taiwan stock market from 1997 to 2000 is a negative event for stockholders. Stocks involved in exchange switching experience negative abcdrmal returns before and after switching. And, in general, liquidity deteriorates after exchange switching. Therefore, TSEC is not absolutely better than OTC from the view of liquidity-providing. Several conclusions are derived in this paper: 1. On average, exchange switching in Taiwan does not create value for stockholders. 2. In general, liquidity deteriorates after switching according to the evidences found in this study with multiple liquidity measures. 3. Liquidity indeed has multiple facets. 4. TSEC is not exactly better than OTC for raising in terms of function of liquidity providing.

本文研究主要在探討以銀行團聯貸宣告下，對台灣地區上市的參貸銀行和借款公司之股東財富有何影響？本研究以事件研究法（Event Study）對標準化異常報酬做檢定，同時由於過去對殘差項估計多是以古典最小平方法來估計，但是實際股票報酬率通常具有尖峰態的胖尾分配，因此本文同時採Bollerslev(1986)的GARCH估計法及傳統古典最小平方法估計，並對結果做一比較；實証結果如下： 本研究得到下列結論： 1、在股價報酬時間數列特性上：對放款銀行之股價報酬而言，呈現異質變異性質者佔近四成，而對借款公司之股價報酬而言，呈現異質變異性質者佔四成，因此在考慮報酬率的特性時需將此考慮各國模型中，但就事件觀察期的顯著性而言，以古典最小平方法估計以異質條件變異數分析法估計的結論上，無論在放款銀行或在借款公司上皆無顯著之差異，可能因為時間數列的時間較短所致。 2、就放款銀行而言，銀行團聯貸之宣告日前一天，即有整個事件期中最強烈的正向反應，但未達顯著水準，而在宣告日前一天至宣告日當天的事件窗口有顯著水準的正向反應，顯示銀行團聯貸宣告所傳達給放款銀行之股東是正面資訊內涵。 3、就借款公司而言，銀行團聯貸之宣告前二天即有強烈的正向反應（但未達顯著水準），但隔天（宣告日前一天）即以整個事件期中最強烈的負向反應（但未達顯著水準）逆轉，而在宣告日前一天至宣告日當天的事件窗口卻有顯著水準的負向反應，顯示銀行團聯貸宣告所傳達給借款公司之股東是負面的資訊內涵。 4、放款銀行在累積異常報酬方面，在宣告日前十八天左右即有資訊揭露的現象，但持續4天之後，隨即有下跌趨勢，至宣告日前二天更跌至谷底，最後在宣告日後二天才轉回來，此現象可能代表投資人對銀行團聯貸之推動，時間拖愈久，對聯貸之成功與否持較悲觀的市場反應，乃至聯貸宣告後二天，才明確的正向反應出來。 5、借款公司在累積異常報酬方面，在宣告日之前即有上漲的趨勢，此現象顯示借款公司之股東對借款公司持較樂觀的市場反應，然宣告日前一天負面反應最強烈，可能顯示聯貸案成功與否會響到借款公司聲譽及資金的調度等方面，但聯貸案成功宣告後，則以更大幅度的正向股價反價，因此聯貸宣告整體而言，對借款公司之股東應為正面的資訊內涵。 6、以橫斷面分析法複迴歸的方式分別探討對放款銀行與對借款公司之異常報酬影響原因，實証結果顯示在放款銀行而言有99..........9%以上的顯著性，表示異常報酬與新銀行是否加入競爭有負向的關係，此現象表示81年新銀行的成立，使得舊有銀行聯貸的利潤受到很大衝擊。而在借款公司而言，銀行團參貸家數，與借款公司之異常報酬無顯著相關性，無法証實「契約彈性假說」，而借款公司之資產規模與舉債能力與異常報酬無顯著水準相關。