This paper treats the question about how the internationally established company, Apple, is affected by intern or extern events when it comes to the trade market. The purpose of the study is to investigate if chosen events create abnormal return on Apples stock market. The chosen research area is Steve Jobs three sick-listings, It-bubble and the purchase of the search engine company Siri. The reason of writing about this is the big interest for the stock market and its function. This study methodological starting position is quantitative done by an event study, with qualitative feature done by an interview with an expertise within this area. When analyzing the empirics, we have used the efficient market theory that says that information should not affect the stock market in the degree that abnormal return creates. Beyond that theory, we have used former research "Stock prices and top management changes" written by Jerold B. Warner and Ross L. that got abnormal return when they did an event study about CEO changes, "CEO change and firm performance in large corporations: succession effects and manager effects", Randolph P. Beatty och Edward J. Zajac. that means that the stock prices affect is different depending on if the shareholders is more prepared to the information, "The stock market psychology" there Gyllenram refers to his theory about people projecting their thoughts and feelings to each other that creates big movements on the stock market and "Beyond Greed and Fear", Shefrin H. that while his study discovered a new theory that he called "the opposite strategy", meaning that a high positive volatility is comply with a negative volatility by the same value. Shefrin also note that new information makes overreaction and vice versa. The conclusion that we can make by this research is that new shocking information has led to overreaction, exactly like Shefrin points out. That means that older information makes less volatility, and we can see this by studying Steve Jobs three sick-listings. The efficient market theory was adaptable on these three events, because abnormal return did not occur. However, we got abnormal return on the other two events, Siri and the It -bubble. We could associate these answers to Shefrin´s theory about overreaction when new information gets public.

I denna studie har aktieutvecklingen hos förvärvade börsnoterade företag vid budets offentliggörande studerats. Företagen som förvärvades under lågkonjunkturen år 2007-2009, och högkonjunkturen år 2001-2004 har undersökts för att se om det finns någon skillnad i aktieprisutvecklingen som skulle kunna bero på vilket tillstånd ekonomin i samhället befinner sig. Därefter utreds om det finns en skillnad beroende på vilken bransch företagen befinner sig i. Studien förankras teoretiskt ur den effektiva marknadshypotesen där en semistark effektiv marknad antas. Denna grad av effektivitet antas vanligen för finansiella marknader och är den form som eventstudier utgår ifrån. Den undersökningsform som används i denna uppsats är en eventstudie och denna statistiska metod mäter marknadens reaktion på ny information. Den abnorma avkastningen har beräknats vilket sedan belysts genom tabeller och diagram, vilka i sin tur tolkats av en analytiker. Studien resulterade i att företagsförvärv i lågkonjunktur har högre abnorm avkastning än uppköp som sker under högkonjunktur. Uppsatsen uppvisade även att kommunikationssektorn hade en högre abnorm avkastning än resterande branscher. / Share development of acquired companies listed at the bearer's publication has been studied. Companies acquired during the recession years 2007-2009 and the boom years 2001-2004 have been studied to see if there is any difference in the share price that would depend on what cyclical the economy in the society is. I have further investigated whether there is a difference depending on what industry the companies are active in. The study is anchored in theory from the efficient market hypothesis in which a semi-strong efficient market is assumed. This degree of efficiency is usually assumed in financial markets and is the form that event studies adopt. The survey form used in this paper is an event study and this statistical method measures the market’s reaction to new information. The abnormal return is calculated which is then illustrated by tables and charts, which in turn is interpreted by an analyst. The study showed that acquisitions in the recession had higher abnormal returns than purchases made during the boom. The paper also showed that the communications companies had a higher abnormal return than the remaining sectors.

I denna uppsats undersöks om världshändelser skapar abnorma effekter hos oljebolags aktiekurser och om dessa effekter ter sig olika beroende på företagens olika storlek. Undersökningen utförs med hjälp av en eventstudie som genomförs på sex oljebolag med tre världshändelser som utgångspunkt. De valda världshändelserna bestod av två naturkatastrofer och en större ekonomisk händelse. Företagen som valdes delades in i två grupper om tre företag, där ena gruppen innehöll de större företagen och den andra gruppen de mindre. Slutsatserna som har kunnat dras av undersökningen är att händelserna i två av de tre undersökta fallen orsakade signifikanta abnorma under- eller överavkastningar hos oljebolagens aktier vilket bevisar en viss ineffektivitet hos marknaden. Det generella utfallet var att den ekonomiska händelsen visade sig ha en större påverkan på aktiekurserna än de två naturkatastroferna hade. Samtidigt kunde det påvisas en större skillnad mellan de större och de mindre företagens aktiekursers reaktioner gällande den ekonomiska händelsen. Resultaten visade att de mindre företagen drabbades hårdare. / This essay examines whether world events create abnormal effects of oil companies stock prices and whether these effects appear different depending on the companies’ different sizes. The analysis is performed using an event study conducted in six oil companies with three world events as a starting point. The selected world events consisted of two natural disasters and a greater economic event. The companies selected were divided into two groups of three companies, in which one group contained the larger companies and the second group the smaller ones. The conclusion that has been drawn from the study is that the events in two of the three cases studied caused significant abnormal deficit or excess returns of oil companies’ shares, which proves certain inefficiency of the market. The general outcome was that the economic event turned out to have a greater impact on the firms’ stock prices than the two natural disasters had. It was possible to distinguish a significant difference between the stock prices reactions of the larger and smaller firms regarding the economic event. The result showed that the smaller companies were affected to a larger extent.