This paper surveys various statistical methods that have been proposed for the examination of the efficiency of financial markets and proposes a novel procedure for testing the predictability of a time series. For illustration, this procedure is applied to Austrian stock return series.

This essay examines the impact of game releases on the Swedish stock market. As previous research has examined product launches and news releases, this thesis intends to investigate game releases by game developer companies such as developers of computer, console or mobile games. Previous research has been based on a business perspective and business valuation, the authors of this thesis intend to examine the individual investor's perspective. The theoretical framework consists of information asymmetry, the signaling model, the effective market hypothesis, random walk hypothesis and market reaction to new products. The study has chosen a deductive quantitative research approach with the event study method. The sample consists of 14 game developer companies in computer, console and mobile games during theperiod 2017–2021 that are listed on the Swedish market, which were observed during a period of 180 days before the event day and 40 days after. The results showed that there is a statistically significant relationship before, after and during the event day for game releases.The period during and after the event day can also be generalized where 9/14 respective 10/14 game developer companies showed statistically significant within the accumulated abnormal return. / Denna uppsats undersöker påverkan av spelsläpp på den svenska aktiemarknaden. Då tidigare forskning har undersökt produktlanseringar och nyhetssläpp ämnar denna uppsats att undersöka spelsläpp av spelutvecklarebolag som utvecklar PC-, konsol eller mobilspel. Tidigare forskning har utgått från ett företagsperspektiv och företagsvärdering, författarna för denna uppsats ämnar undersöka den individuella investerarens perspektiv. Det teoretiska ramverket består av informationsasymmetri, signaleringsmodellen, den effektiva marknadshypotesen, random walk hypothesis och marknadsreaktion till nya produkter. Studien har en deduktiv kvantitativa forskningsansats med eventstudie metoden. Urvalet består av 14 spelutvecklarebolag inom dator-, konsol- och mobilspel under tidsperioden 2017–2021 som är börsnoterade på den svenska marknaden. Dessa bolag observerades under en tidsperiod 180 dagar innan eventdagen och 40 dagar efter. Resultatet visade på att det finns ett statistiskt signifikant samband innan, efter och under eventdagen för spelsläpp. Perioden under och efter eventdagen kan även generaliseras där 9/14 respektive 10/14 spelutvecklarbolag visade på statistisk signifikant inom den ackumulerade abnormala avkastning.

Submitted by Ludmilla Oliveira Ambrosi Sales (ludy.sales@gmail.com) on 2017-02-19T02:58:28Z No. of bitstreams: 1 Dissertação de Ludmila_FGV.pdf: 1634569 bytes, checksum: f69fd3c3e31851a5d2a8496dbd9c50a8 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Trabalho submetido duas vezes. on 2017-02-20T16:33:52Z (GMT) / Submitted by Ludmilla Oliveira Ambrosi Sales (ludy.sales@gmail.com) on 2017-02-20T21:43:17Z No. of bitstreams: 1 Dissertação de Ludmila_FGV_.pdf: 2700997 bytes, checksum: 502da2dea23764b52c65a0ab70a00a9f (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Ludmilla, Está correto, porém, o código da ficha catalográfica (CDU 336.76) deve estar ao lado direito da ficha. Aguardo on 2017-02-20T21:48:45Z (GMT) / Submitted by Ludmilla Oliveira Ambrosi Sales (ludy.sales@gmail.com) on 2017-02-20T23:06:20Z No. of bitstreams: 1 Dissertação de Ludmila_FGV_.pdf: 2701182 bytes, checksum: c86ac2ab833162046024483778a8b39a (MD5) / Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2017-02-20T23:28:14Z (GMT) No. of bitstreams: 1 Dissertação de Ludmila_FGV_.pdf: 2701182 bytes, checksum: c86ac2ab833162046024483778a8b39a (MD5) / Made available in DSpace on 2017-02-21T18:12:36Z (GMT). No. of bitstreams: 1 Dissertação de Ludmila_FGV_.pdf: 2701182 bytes, checksum: c86ac2ab833162046024483778a8b39a (MD5) Previous issue date: 2017-01-27 / This paper revisits the theory of market efficiency and analyzes the Brazilian capital market for a more recent period in order to verify if the improvement pointed out in the study by Bonomo (2002) persists, that is, if the reduction of inefficiency in the course of the Time is robust. The existence of autocorrelation may be an indication of abnormal returns if the strategies adopted exploit this correlation and generate an abnormal return. The autocorrelation tests adopted in the random walk literature, for the most part, do not take into account the Heteroscedasticity characteristic of financial assets and, therefore, this work seeks to apply Bartlett’s formula for non-linear processes in order to verify if existence Of autocorrelation between the Brazilian papers analyzed and if this is enough to generate an extraordinary return. Traditional statistical and correlation tests were applied together with random walk tests to verify if the Brazilian capital market is efficient in its weak form. / Este trabalho revisita a teoria de eficiência de mercado e analisa o mercado de capitais brasileiros para um período mais recente a fim de verificar se a melhora apontada no estudo feito por Bonomo (2002) persiste, ou seja, se a redução da ineficiência no decorrer do tempo é robusta. Foram selecionadas 15 ações brasileiras que compunham o IBOVESPA de Maio 2016 e o período de análise compreende Janeiro de 2000 a Maio 2016. A existência de autocorrelação pode ser um indício de retornos anormais caso as estratégias adotadas explorem essa correlação e consigam gerar um retorno anormal. Os testes de autocorrelação adotados na literatura de passeio aleatório, em sua maioria, não levam em conta a característica de Heterocedasticidade dos ativos financeiros e, por isso, este trabalho busca aplicar a fórmula de Bartlett para processos não lineares a fim de verificar se a existência de autocorrelação entre os papéis brasileiros analisados e se esta é suficiente para gerar um retorno extraordinário. Testes estatísticos tradicionais e de correlação foram aplicados juntamente a testes de random walk para verificar se o mercado de capitais brasileiro é eficiente na sua forma fraca.