This research has studied the relationship between insider trading activity and its effect on the level of informational efficiency. The authors have used insider data from Finansinspektionen and data regarding stock prices, market capitalization and GDP from Thomson Reuters Datastream. The sample includes 193 companies on the Swedish stock exchange for a period of 10 years. A Variance Ratio test employed on moving sub-sample windows was used to establish the level of time-varying informational efficiency, which subsequently was used in an OLS-regression as a dependent variable. The result of the regression implies a negative effect on firm price information efficiency by insider purchasing, while selling has a positive effect. This can be concluded using a confidence level of 99%. The results are interesting since they imply an asymmetrical effect of insider trading on informational efficiency, while current insider legislation treats buying and selling by insiders equal. Thus, the results are of interest in future adjustments of laws regulating insider trading.

Magister Commercii - MCom / This research attempts to discover whether the Adaptive Market Hypothesis theory is applicable in the South African financial market and explores the innovation and cyclical profitability implications of the Adaptive Market Hypothesis theory. This is achieved in two parts: first by determining if returns follow a random walk or not and second by analysing the consistency of technical and fundamental factors to explain the cross-section of equity returns between 1 January 1998 to 31 December 2017. The tests of stock return dependency include a total of five tests on the average monthly returns for each stock in the ALSI covering normality and random walk theory for the duration of the two sub-periods and entire examination period.

We evaluate the validity of the Adaptive Market Hypothesis (AMH) in a Swedish context by testing for stock return predictability on the OMXS30 stock index between 1986 and 2014 using daily returns and monthly two year moving subsamples. To our knowledge, this is the first study to evaluate the AMH in a Swedish context. Three tests for linear independence based on Lo and MacKinlay (1988) variance ratio test, namely the Chow and Denning joint test as well as Wright (2000) joint rank and sign tests are used. We also test for non-linear independence using the BDS test statistics. Presented in our findings is evidence of time-varying predictability where stock returns go through periods of return predictability and non-predictability. When evaluating the different market conditions (volatility, bull, bear, up, down and normal markets) we find that these different market conditions govern the degree of stock return predictability in different ways. Our findings support the AMH on the OMXS30 stock index and in contrast to previous research regarding market efficiency on the Swedish stock market, we do not find persistent stock return predictability over the short and long term.

Trenden inom världsekonomin har på senare år indikerat på en mognad där tillväxten ligger på låga tal historisk. Detta har tvingat centralbanker runt omkring jorden att drastiskt ta till åtgärder för att stimulera tillväxten. Reporäntan har använts som det mest centrala instrumentet för detta ändamål. Sverige är ett levande exempel på detta, där de har sänkt räntan lägre än den fruktade nollnivån och har i dagsläget en ränta på -0,5 %. Effekterna av reporänteförändringar på aktievärdering har studerats brett och den ackumulerade åsikten bland forskare är att räntan påverkar aktiemarknaden direkt. De historiska studierna som har utförts fokuserar på hur marknaden som helhet påverkas där de individuella företagseffekterna hamnar i skymundan. Därför har denna studie fokuserat på att undersöka dessa branschrelaterade effekter av en ränteförändring på individuella företag inom de valda branscherna. Detta område har undersökts med hjälp av en eventstudie.  Resultaten från studien visar på homogena effekter för mindre bolag där dessa får en större påverkan vid förändringar än stora bolag. Detta visar sig även mellan de olika branscherna. De observerade branscherna är sällanköpsvaror och dagligvaror, de branschspecifika effekterna som studien visar är att dagligvaror påverkas signifikant mer än sällanköpsvaror. Vidare visar resultatet att företagsstorlek har en större påverkan än branschtillhörighet, där small-cap bolag inom sällanköpsvaror har större påverkan än large-cap bolag inom dagligvaror. En negativ förändring går även att hänvisa till mer homogena rörelser för branscherna samt de olika storlekarna. Vidare gav positiva nyheter en mer heterogen rörelse där de mindre bolagen ej korrelerade med dem större. / In recent years, the trend in the world economy has indicated a maturity in growth which is low in historical terms. This has forced central banks around the world to drastically act to stimulate growth. The prime rate has then been used as the most central instrument for this purpose. Sweden is a living example of this as they have lowered interest rates below the dreaded zero level and currently have an interest rate of -0.5 %. The effects of prime rate changes on stock valuation have been studied widely, and the accumulated opinion among researchers is that interest rates directly affect the stock market. The historical studies that have been carried out focus on how the market as a whole is affected where individual effects on businesses end up in the dark. Therefore, this study has focused on investigating these industry-related effects of an interest rate change on individual companies in the chosen industries. The results from the study show homogenous effects for smaller companies, where the impact is greater on them in addition to larger companies. This is also apparent between the different industries. This area of concerns has been studied with an event study. The observed industries are consumer discretionary and commodities, the industry-specific effects shown by the study are that commodities are significantly more affected than consumer discretionarys’. Furthermore, the results show that company size is a greater indicator than industry due to the greater effect on small companies within consumer discretionary than on larger companies in the commodities sector. A negative change can also be referred to more homogeneous movements for the industries as well as the different business sizes. In addition, positive news gave a more heterogeneous move where the smaller companies did not correlate with the larger ones.