Prior studies have shown that returns exhibit certain predictable patterns that are inconsistent with the mainstream finance theory. In this thesis, I explore the behaviour of returns following three different types of market events with a particular focus on behavioural and non-behavioural factors that are attributable to the predictability of post-event returns. This thesis consists of three self-contained empirical essays. The first essay examines the information role of large S&P500 futures trades (commercial, noncommercial, dealers, asset managers, and hedge funds) in shaping future index returns. I find that commercial firms’ net trading level appears positively correlated with future index returns but the relationship is not stable across time. Based on more recent data, hedge funds appear superior in terms of access to information and/or trading ability but this advantage is only preserved at high frequency. Therefore, the current weekly Commitment of Traders (COT) report - published with a three-day delay - prevents timely public access to this type of information. Also, trading signals based on two of the more popular position-based sentiment indicators do not produce significant average returns. Overall, this calls into question the reliability of COT-based trading signals used by market professionals. The second essay studies the impacts of short sellers’ trading in shaping the behaviour of stock returns following extreme price moves using data from stock market in mainland China where short sales were initially prohibited. Extreme price moves occurring under non-prohibitive/prohibitive short-sale constraints are defined as shortable/non-shortable events. I find shortable events exhibit less post-event price drift/reversals than non-shortable ones, indicating an increase in the efficiency of stock prices reacting to unexpected events. Further analysis of short sellers’ trading activities on the price event days suggests that they are successful in trading informed price shocks but not in trading uninformed ones. Finally, I find evidence of massive short-covering that amplifies price shocks. The third essay investigates investors’ reaction to stock market rumours using data from China where listed companies are required to clarify rumours appearing in the media. I find that post-clarification abnormal returns exhibit continuation of pre-clarification momentum for rumours that are not denied by the listed companies and reversals for those which are denied. These results suggest that investors are unable to distinguish the reliable rumours from the false ones, as they under-react to rumours containing material information and over-react to those without. Further regression analyses on post-clarification abnormal returns using various subsamples of rumour events show that investors respond more efficiently to rumours when they are more informed about news topics or the rumoured companies.

This thesis is both an ethnographic story about people with albinism in Tanzania and a reflection on how that story may be used to generate understanding and support in the wider world. In much of sub-Saharan Africa people with albinism face discrimination and even violence at all levels of society. During seven months in 2021/2022 I lived in northern Tanzania and regularly spent time with a community of children with albinism and the woman who shelters them. I got to know these individuals through conversations, interviews, grocery shopping, cooking, and eating together and celebrating Christmas and other holidays. All the while, I also sought to be in solidarity with my hosts, by telling their story in various forms and raising funds for them in Sweden. A central research question of the thesis is how one tells a story about vulnerable individuals without diminishing their dignity or violating ethical standards of academia, journalism, and humanitarianism. I consider four types of public response to my various acts of ethnographic storytelling, and I reflect upon persistent dilemmas.

Os modelos de Daley-Kendall e Maki-Thompson são os dois modelos estocásticos para difusão de rumores mais citados até o momento. Em ambos, uma população finita fechada e totalmente misturada é subdividida em três classes de indivíduos denominados ignorantes, informantes e contidos. Depois de um rumor ser introduzido na população, difunde-se através desta seguindo determinadas regras que dependem da classe à qual a pessoa que sabe do rumor pertence. Tanto a proporção final de indivíduos que nunca chegam a conhecer o rumor quanto o tempo que este demora em ser difundido são variáveis de interesse para os modelos propostos. As técnicas encontradas na literatura para estudar modelos de rumores são o princípio de difusão de constantes arbitrárias; argumentos de martingais; o método de funções geradoras e a análise de versões determinísticas do processo. Neste trabalho apresentamos uma alternativa para essas técnicas baseando-nos na teoria de cadeias de Markov \"density dependent\'\'. O uso desta nova abordagem nos permite apresentar resultados assintóticos para um modelo geral que tem como casos particulares os famosos modelos de Daley-Kendall e Maki-Thompson, além de variações de modelos de rumores apresentados na literatura recentemente. / Daley-Kendall and Maki-Thompson models are the two most cited stochastic models for the spread of rumours phenomena, in scientific literature. In both, a closed homogeneously mixing population is subdivided into three classes of individuals called ignorants, spreaders and stiflers. After a rumor is introduced in the population, it spreads by following certain rules that depend on the class to which the individual who knows the rumor belongs. Both the final proportion of the population never hearing the rumor and the time it takes are variables of interest for the proposed models. The main tools used to study stochastic rumours have been the principle of the diffusion of arbitrary constants, martingale arguments, generating functions and the study of analogue deterministic versions. Relying on the theory of density dependent Markov chains, we present an alternative to these tools. This approach allows us to establish asymptotical results for a general model that has as particular cases the classical Daley-Kendall and Maki-Thompson models, and other variations for rumour models reported in the literature recently.

Os modelos de Daley-Kendall e Maki-Thompson são os dois modelos estocásticos para difusão de rumores mais citados até o momento. Em ambos, uma população finita fechada e totalmente misturada é subdividida em três classes de indivíduos denominados ignorantes, informantes e contidos. Depois de um rumor ser introduzido na população, difunde-se através desta seguindo determinadas regras que dependem da classe à qual a pessoa que sabe do rumor pertence. Tanto a proporção final de indivíduos que nunca chegam a conhecer o rumor quanto o tempo que este demora em ser difundido são variáveis de interesse para os modelos propostos. As técnicas encontradas na literatura para estudar modelos de rumores são o princípio de difusão de constantes arbitrárias; argumentos de martingais; o método de funções geradoras e a análise de versões determinísticas do processo. Neste trabalho apresentamos uma alternativa para essas técnicas baseando-nos na teoria de cadeias de Markov \"density dependent\'\'. O uso desta nova abordagem nos permite apresentar resultados assintóticos para um modelo geral que tem como casos particulares os famosos modelos de Daley-Kendall e Maki-Thompson, além de variações de modelos de rumores apresentados na literatura recentemente. / Daley-Kendall and Maki-Thompson models are the two most cited stochastic models for the spread of rumours phenomena, in scientific literature. In both, a closed homogeneously mixing population is subdivided into three classes of individuals called ignorants, spreaders and stiflers. After a rumor is introduced in the population, it spreads by following certain rules that depend on the class to which the individual who knows the rumor belongs. Both the final proportion of the population never hearing the rumor and the time it takes are variables of interest for the proposed models. The main tools used to study stochastic rumours have been the principle of the diffusion of arbitrary constants, martingale arguments, generating functions and the study of analogue deterministic versions. Relying on the theory of density dependent Markov chains, we present an alternative to these tools. This approach allows us to establish asymptotical results for a general model that has as particular cases the classical Daley-Kendall and Maki-Thompson models, and other variations for rumour models reported in the literature recently.

Avhandlingen beskriver och analyserar hur skolvalfriheten som policy, det vill säga uppfattad möjlighet och hot tar sig i uttryck i vardaglig praktik. Aspekter av diskurser, praktiker analyseras i avhandlingen utifrån olika aktörers handlingshorisonter. Avhandlingens kontext består av en urbant belägen lokal skolmarknad, inom vilken aktörers praktiker och strategier undersöks. Avhandlingen behandlas således hur ungdomar, familjer och skolprofessionella navigerar skolvalfriheten i en alltmer polariserad och storstadsregion. Teoretiskt ramas studien in av Pierre Bourdieu sociologi samt koncept från det kulturgeografiska fältet. Metodeoliskt bygger avhandlingen på empiri insamlat med etnografiska metoder under läsåret 2012-2013. I de fem empiriska kapitlen diskuteras hur föreställda geografier, skolhabitus, rykten och symboliska gränser förhandlas av studiens aktörer. I det avslutande kapitlet diskuteras och analyseras avhandlingens främsta bidrag. Kapitlet lyfter också några frågeställningar som måste adresseras för ett mer jämlikt utbildningssystem. / This thesis explores and analyses how school choices are made and perceived in an urban local school market. The thesis uses concepts from the French sociologist Pierre Bourdieu and theories working with the concept of place and space. Using ethnographical methods, it explores the geography of school choice, while the empirical material describes and analyses school choices in a local school market structured by socio-economic as well as symbolic boundaries. The five empirical chapters discuss and analyse imaginary geographies, school habitus, hot and cold knowledge, and symbolic boundaries. The concluding chapter discusses the main findings and addresses some questions regarding how to make the educational system more equitable.

This study examined the alleged prevalence of Satanism in Zambia, with a particular reference to the Kabwe District during the period 2010-2013. The overall objective was to ascertain the claims and speculations on the alleged prevalence of Satanism in the district of Kabwe. The claims about the alleged prevalence of Satanism and the satanic scare were found by this study to be a reality in Kabwe, with eighty-eight per cent (88%) of the respondents acknowledging the alleged prevalence of the phenomenon. People’s knowledge of Satanism was mainly through rumours, messages from Churches and the electronic media. Studies on rumours (by Stephen Ellis, Gerrie Ter Haar and Jeffrey Victor) have shown that rumours can be investigated in the search for facts, especially rumours that offer plausible explanations for people’s shared anxieties. The above mentioned scholars argue that with efforts at corroboration, such as by interviewing key informants, the researcher can seek credibility on prevailing rumours by verifying or dismissing mere rumours from true stories. The assertions from scholars above justified the use of rumours as a methodological tool in this study. From sources of information the study relied on, claims about the alleged prevalence of Satanism in the district were investigated. The study refuted the satanic claims in a number of cases that were analysed, because they were mostly based on ‘pious legends’ hence lacked objective evidence. From the few incidents that suggested the prevalence of Satanism, there were still two basic problems faced in assessing their credibility: the first being the difficulty in determining the reliability of the confessions from informants who in this case either claimed they were ex-Satanists or served on behalf of Satanists. The second problem consisted in what seemed to be the inconsistency in the explanations of motives behind human killings found in the ritual murders. Some explanations did not suggest satanic motives. One example of refuted claims concerned the two locations within Kabwe district which were highly rumoured to be sites for Satanists, which were found by this study to be Freemasonry Lodges, contrary to what was rumoured.From the findings of this study, it was believed that people joined Satanism either because of the greedy for riches or to avoid poverty. It was also believed that other peoples joined Satanism unconsciously through luring methods used by Satanists. The study also found the satanic scare to have effects on the lives of people in the district. For example, it caused some people to become more committed Christians in their defence against the alleged satanic forces. Because people had associated riches to Satanism, certain individuals avoided getting rich for fear of being labelled ‘Satanists’. / Religious Studies & Arabic / D. Litt. et Phil. (Religious Studies)

This study examined the alleged prevalence of Satanism in Zambia, with a particular reference to the Kabwe District during the period 2010-2013. The overall objective was to ascertain the claims and speculations on the alleged prevalence of Satanism in the district of Kabwe. The claims about the alleged prevalence of Satanism and the satanic scare were found by this study to be a reality in Kabwe, with eighty-eight per cent (88%) of the respondents acknowledging the alleged prevalence of the phenomenon. People’s knowledge of Satanism was mainly through rumours, messages from Churches and the electronic media. Studies on rumours (by Stephen Ellis, Gerrie Ter Haar and Jeffrey Victor) have shown that rumours can be investigated in the search for facts, especially rumours that offer plausible explanations for people’s shared anxieties. The above mentioned scholars argue that with efforts at corroboration, such as by interviewing key informants, the researcher can seek credibility on prevailing rumours by verifying or dismissing mere rumours from true stories. The assertions from scholars above justified the use of rumours as a methodological tool in this study. From sources of information the study relied on, claims about the alleged prevalence of Satanism in the district were investigated. The study refuted the satanic claims in a number of cases that were analysed, because they were mostly based on ‘pious legends’ hence lacked objective evidence. From the few incidents that suggested the prevalence of Satanism, there were still two basic problems faced in assessing their credibility: the first being the difficulty in determining the reliability of the confessions from informants who in this case either claimed they were ex-Satanists or served on behalf of Satanists. The second problem consisted in what seemed to be the inconsistency in the explanations of motives behind human killings found in the ritual murders. Some explanations did not suggest satanic motives. One example of refuted claims concerned the two locations within Kabwe district which were highly rumoured to be sites for Satanists, which were found by this study to be Freemasonry Lodges, contrary to what was rumoured.From the findings of this study, it was believed that people joined Satanism either because of the greedy for riches or to avoid poverty. It was also believed that other peoples joined Satanism unconsciously through luring methods used by Satanists. The study also found the satanic scare to have effects on the lives of people in the district. For example, it caused some people to become more committed Christians in their defence against the alleged satanic forces. Because people had associated riches to Satanism, certain individuals avoided getting rich for fear of being labelled ‘Satanists’. / Religious Studies and Arabic / D. Litt. et Phil. (Religious Studies)

Social networks play an important role in disseminating a piece of information in a population. Companies advertising a newly launched product, movie promotion, political campaigns, social awareness campaigns by governments, charity campaigns by NGOs and crowd funding campaigns by entrepreneurs are a few examples where an entity is interested in disseminating a piece of information in a target population, possibly under resource constraints. In this thesis we model information diffusion in a population using various epidemic models and study optimal campaigning strategies to maximize the reach of information. In the different problems considered in this thesis, information epidemics are modeled as the Susceptible-Infected, Susceptible-Infected-Susceptible, Susceptible-Infected-Recovered and Maki Thompson epidemic processes; however, we modify the models to incorporate the intervention made by the campaigner to enhance information propagation. Direct recruitment of individuals as spreaders and providing word-of-mouth incentives to the spreaders are considered as two intervention strategies (controls) to enhance the speed of information propagation. These controls can be implemented by placing advertisements in the mass media, announcing referral/cash back rewards for introducing friends to a product or service being advertised etc. In the different problems considered in this thesis, social contacts are modeled with varying levels of complexity---population is homogeneously mixed or follows heterogeneous mixing. The solutions to the problems which consider homogeneous mixing of individuals identify the most important periods in the campaign duration which should be allocated more resources to maximize the reach of the message, depending on the system parameters of the epidemic model (e.g., epidemics with high and low virulence). When a heterogeneous model is considered, apart from this, the solution identifies the important classes of individuals which should be allocated more resources depending upon the network considered (e.g. Erdos-Renyi, scale-free) and model parameters. These classes may be carved out based on various centrality measures in the network. If multiple strategies are available for campaigning, the solution also identifies the relative importance of the strategies depending on the network type. We study variants of the optimal campaigning problem where we optimize different objective functions. For some of the formulated problems, we discuss the existence and uniqueness of the solution. Sometimes our formulations call for novel techniques to prove the existence of a solution.