Abstract   Background: The dividend ex-day effect is the tendency of the stock price drop on the ex-day to be less than the dividend per share. This inclination is contrary to established theory of rational investor behaviour and is, thus, considered an anomaly in capital markets. The phenomenon was first observed more than half a century ago and has puzzled researchers ever since, resulting a myriad of theories trying to explain its cause. Nevertheless, the dividend ex-day effect still stands without a conclusive explanation. In Sweden, few studies have been conducted and none succeeds in explaining the phenomenon. In a recent addition to the many explanatory theories, Efthymiou and Leledakis (2014) propose the disposition effect as the driving factor behind the dividend ex-day effect. Compelling evidence for this notion is provided in an empirical study of the US market, warranting the consideration of a similar investigation in the Swedish market.   Purpose: The purpose of this study is to examine the relationship between the dividend ex-day effect and the disposition effect in the Swedish stock market. Method: This study is conducted using a deductive approach and a quantitative research strategy. Secondary data of OMXS stocks during the 2013-2017 period is gathered from Thomson Reuters Datastream. To fulfil the purpose, one sample t-tests and regression analyses are performed. Conclusion: Statistically significant results confirm that there is a pervasive dividend ex-day effect on the OMXS market. From here, it is found that there is a substantial difference in the price drop between stocks based on their performance: winning stocks display a higher price drop on the ex-day compared to losing stocks. Regression analyses indicate a positive relationship between the dividend ex-day effect and the disposition effect. Some evidence, although not statistically significant, suggest that for a specific stock, the price drop will be greater in times when the stock has had positive returns compared to when it has had negative returns. A remarkable finding in this study is that all tests indicate that the positive relationship between the dividend ex-day effect and the disposition effect appears to be fading out as the holding period of stocks gets longer.

Bakgrund: En fungerande kapitalmarknad är en förutsättning för en nations innovation,vilket i sin tur är fundamentalt för att uppnå ekonomisk tillväxt. Därav blir förståelsen för hurkapitalmarknaden fungerar av största vikt. En av de vanligaste frågorna investerare ochforskare ställer sig är huruvida marknader är effektiva? Kan investerare utgå ifrån attkapitalmarknaden är effektiv och att alla handlar på samma information? Frågan är viktigeftersom kapitalmarknaden är uppbyggd på ett förtroende hos allmänheten, om dettaförtroende raseras kan det få förödande konsekvenser för nationen, utifrån svårigheter medkapitalallokeringen. Denna studie undersöker, med utgångspunkt från effektiva marknader,fenomenet kallat ex-dagseffekten. Finns det prisavvikelser på marknaden och iförekommande fall, finns det en förklaring till detta? Utifrån det undersöker studien specifiktmikrostrukturen som förklaring till den potentiella prisavvikelsen. Syfte: Syftet med studien är att undersöka, analysera, samt förklara förekomsten av exdagseffektenoch dess relation med mikrostrukturen på OMX Stockholm Large Cap,respektive Mid Cap och Small Cap. Metod: Utifrån studiens behov att sammanställa en större mängd data har en kvantitativforskningsstrategi använts. Studiens sekundärdata är insamlad för utdelande bolag noteradepå OMX Stockholm Large, Mid samt Small Cap mellan årtalen 2016 och 2019. Insamladdata har sedan sammanställts till paneldata, vilken ligger till grund för studiens t-test samtmultipla regressioner. Slutsats: Utifrån studiens t-test påvisas att ex-dagseffekten föreligger på studiens utvaldamarknad. Vidare, utifrån studiens regressioner utläses det att mikrostrukturen har en negativpåverkan på PDR. Då förekomst av mikrostrukturen påvisas kan studien inte uttala sig omhuruvida marknaden som undersökts är ineffektiv eller ej. / Background: A functioning capital market is a prerequisite for the innovation of a nation,which in turn is fundamental to achieve economic growth. Hence, the understanding of howthe capital market operates becomes of paramount importance. One of the most commonquestions investors and researchers ask themselves is whether markets are efficient? Caninvestors assume that the capital market is efficient and that everyone trades on the sameinformation? The question is important because the capital market is built upon publicconfidence, and if this trust is destroyed, it can have devastating consequences for the nation,based on difficulties with capital allocation. This study examines, based on efficient markets,the phenomenon called the ex-day effect. Are there price deviations in the market, and ifapplicable, is there an explanation for this? Based on this, the study specifically examines themicrostructure as an explanation for the potential price deviation. Purpose: The purpose of the study is to investigate, analyze, and explain the existence of theex-day effect and its relationship with the microstructure of OMX Stockholm Large Cap, MidCap and Small Cap. Method: Based on the study's need to compile a larger amount of data, a quantitativeresearch strategy has been used. The study's secondary data is collected for distributingcompanies listed on OMX Stockholm Large, Mid and Small Cap between the years 2016 and2019. Collected data has then been compiled into panel data, which is the basis for the study'st-test and multiple regressions. Conclusion: Based on the study's t-test, it is demonstrated that the ex-day effect is present inthe study's selected market. Furthermore, based on the regressions models the study used, itcan be deducted that the microstructure has an impact of PDR. Since the presence of themicrostructure is detected, the study cannot comment on whether the market examined isinefficient or not.