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Investeringar i aktier eller aktiefonder kan få ens pengar att växa genom den kumulativa avkastning som genereras. Genom ränta-på-ränta-effekten kan en liten ökning i avkastning från dessa investeringar få en stor effekt över en lång tidsperiod. På grund av detta etablerar många investerare strategier för att försöka uppnå en högre avkastning än den generella aktiemarknaden. Att slå marknaden har historiskt sett varit svårt vilket går i linje med det rådande paradigmet om att marknader är effektiva. Empirisk forskning har dock visat på återupprepande prismönster, som inneburit att det funnits möjligheter att strategiskt och systematiskt investera för att generera en högre riskjusterad avkastning än marknaden. Dessa prismönster kallas för anomalier och när de är tidsbaserade benämns de vanligtvis som kalendereffekter. Syftet med studien var att undersöka huruvida kalendereffekter även varit förekommande på marknader med mindre utvecklade institutioner och begränsad tidigare forskning. Studien är avgränsad till aktiemarknader i Afrika och har ställts i relation till motsvarande marknader i några av västvärldens mest välutvecklade ekonomier. En jämförelse har gjorts för att undersöka vart och vilka kalendereffekter som funnits samt hur resultatet skiljer sig mellan Afrika och västvärlden. Studien omfattar en tidsperiod från år 2000 fram till 2020. Resultatet visar något vanligare och mer signifikanta kalendereffekter på de afrikanska marknaderna men inte någon annan tydlig övergripande skillnad vid jämförelse med de västerländska marknaderna. Långa positioner vid månadsskiftet och efterföljande dagar alternativt vid slutet av handelsveckan har kunnat ge en högre riskjusterad avkastning än den generella marknaden i flera länder. Under tidsperioden finns det således belägg för att överavkastning kunnat uppnåtts på ett flertal afrikanska aktiemarknader genom systematiskt planerade investeringar. / Investments in equities or equity funds can help to make your money grow through the cumulative returns generated. Through compound interest, a small increase in return on these investments can have a large effect over a long period of time, resulting in many investors establishing strategies to achieve a higher return than the general stock market. Beating the market has historically been difficult which supports the prevailing paradigm that markets are efficient. However, empirical research has shown recurring price patterns, implying that there have been opportunities to strategically and systematically invest to generate a higher risk-adjusted return than the market. These price patterns are called anomalies and when time-based, are usually referred to as calendar effects. The purpose of this study was to examine whether calendar effects were also present in markets with less developed institutions and limited previous research. The study is focused on stock markets in Africa, which have been compared to corresponding markets in some of the most developed economies in the Western world. A comparison has been made to examine where and what calendar effects existed and how the results differ between Africa and the Western world. The study covers a period from 2000 to 2020. The results show slightly more common and significant calendar effects in the African markets, but no other clear overall difference was observed when compared with the Western markets. Long positions at the end of the month and subsequent days, alternatively at the end of the trading week, have been able to produce a higher risk-adjusted return than the general market in several countries. Thus, during this time period, there is evidence that excess returns could have been achieved in a number of African stock markets through systematically planned investments.

Purpose: The purpose of this thesis is to study the possible existence of day-of-the-week effects and month-of-the-year effects in the Singapore stock market over the period January 1st 1993 to December 31st 2011. The findings are analysed with the intention of developing investment strategies and to investigate if behavioural finance can help to explain the existence of seasonal anomalies.  Background: A number of previous studies have found evidence of seasonal anomalies in global stock markets, and by challenging the core assumptions of market efficiency, such anomalies may make it possible to predict the movement of stock prices at certain periods during the year. Consequently, there may be substantial profit-making opportunities that clever investors can benefit from, raising two important questions: (1) can such anomalies be strategically used to outperform the market and (2) why do such cyclical return patterns exist? Method: Daily closing prices from the Singapore Straits Times Index (STI) are used to compute average daily and monthly returns, which are further analysed through the use of statistical significance analysis and hypothesis testing to identify the possible existence of day-of-the-week effects and month-of-the-year effects in the Singapore stock market.  The results of the statistical investigation are used to develop investment strategies that are designed to take advantage of both positive and negative effects, and the theories of behavioural finance are applied to help explain why seasonalities occur at certain points in time. Conclusions: This study finds evidence of several seasonal anomalies in the Singapore stock market. Both day-of-the-week effects and month-of-the-year effects are present in the STI over the full sample period. Many of these effects can be explained by behavioural finance, and used to develop investment strategies that outperform the market.

本文以 GJR-GARCH 為分析模型，針對所選八家台灣上市公司股價所計算之每日對數報酬率(daily log returns)，對於各種不斷到達的新增訊息所引起的波動反應。所納入條件變異數方程式的訊息到達(解釋變數)分別為：(1)同日成交數量(2)成交量變動率(3)星期一與星期五之日曆效應(4)不同權值規模(size-based)投資組合間的波動外溢效果。研究結果發現(1)同日成交量對於台股權值較低的小公司，有能力捕捉其波動性，但是對於權值偏高的大公司，其解釋能力顯有不足(2)成交量變化普遍會導致公司報酬率的波動(3)臺灣股市波動性並不具有星期五效應，至於星期一效應也只出現在部分的小公司(4)不同規模的投資組合間雖然互有波動外溢現象，但其不對稱性非常明顯， 亦即訊息到達後，先造成大公司股價的波動，此波動再進而影響到小公司，引起小公司股價的波動。 / Applying the GJR-GARCH model to the daily returns of eight selected firms from Taiwan stock market, this paper examines response of variance volatility to various information arrivals which separately include (1) concurrent trading volume (2) change in trading volume (3) calendar effects, especially Modnay and Friday effects, and (4) asymmetric volatility spillover between two sized-based portfolios. The results find that concurrent trading volume as a proxy of information arrival dramatically reduces volatility persistence of the small firm's conditional variance, but has little influence on large firm's, and change in trading volume cause significant change in conditional variance. Although there is a conjecture that the volatility in stock markets may be higher on Monday and Friday, it can't be found in this study. The results also strongly support that the volatility spillover effect from larger to small portfolio is more significant than that from smaller to large portfolio.