The Best PhD Thesis in the Faculties of Architecture, Arts, Business & Economics, Education, Law and Social Sciences (University of Hong Kong), Li Ka Shing Prize, 2005-2006. / published_or_final_version / abstract / Business / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Economics and Finance / Doctoral / Doctor of Philosophy

published_or_final_version / Economics and Finance / Doctoral / Doctor of Philosophy

The purpose of this study is to investigate the daily return behavior of underlying common stocks in the period surrounding the option expiration date. A second purpose is to determine the variables that may be causing the differential capital market effect across firms. The hypothesis of a negative return effect in the expiration week followed by a positive effect in the subsequent week is tested first. It is shown that this pattern should be expected due to the enhanced opportunity for and profitability of position unwinding, arbitrage and manipulation activity as the expiration date approached. The study period covers 32 expiration periods from 1978 through 1981 and involves a sample of 138 underlying stocks. The study employs the market model for generating abnormal returns on a daily basis. The results support the hypothesis and in particular show that the most significant negative return behavior occurs on Thursday and Friday of the expiration week. The second phase of the study correlates, via a cross-sectional multiple regression model, the suggested expiration induced events of position unwinding, arbitrage and manipulation activities with the return behavior of the underlying stocks. It is hypothesized that those common stocks which exhibit the greatest negative returns in the expiration week are those stocks and related call options that are most heavily involved in position unwinding, arbitrage and manipulation activities. Trading volume in both the underlying stock and the options is suggested as a surrogate for these three activities. Therefore, volume is negatively related to underlying stock returns. Two additional explanatory variables of the expiration week returns are included in the regression model. A negative relationship is hypothesized if options are dually listed and a positive relationship if puts are traded. The results of the tests generally support these hypothesized functional relationships. The study concludes that, although significant abnormal returns and explanatory variables are found, the magnitudes are probably not large enough to profitably exploit after paying transaction and search costs. As puts trading appears to offset the market inefficiencies caused by call option trading, the concern of regulators that options trading unduly affects stock prices seems unwarranted.

Ph.D. / This thesis investigates the impact of domestic and foreign financial crises on volatility dynamics in South Africa. In a sample ranging from January 1994 to March 2009, Chapter 2 provides empirical support for the theory that domestic currency crises are associated with significant structural changes in daily exchange rate volatility. Speciacally, crisis periods coincide with large positive shifts in unconditional variance. Using this fact, we propose a new method - the structural change generalised conditional heteroskedasticity, or SC-GARCH, model - for identifying precise start- and end-dates for crises. Chapter 3 studies volatility transmission within SA from October 1996 to June 2010. Using a generalised version of the vector autoregressive (VAR) approach, time-varying and bidirectional volatility spillover indices are esti- mated for domestic currency, bond and equity markets. The results identify equities as the primary source of volatility transfer to other asset classes. At di erent points in time, spillovers are responsible for anywhere between 7.5 and 65 percent of system-wide volatility. Local maxima in spillover magni- tudes are estimated during domestic, as well as foreign crisis periods. Chapter 4 estimates time-varying comovement between SA and world volatilities during the period from 1994 to 2008. A dynamic factor model (FM) is used to extract three latent global volatility factors from a data panel which is representative of the world equity market portfolio. Relative to most other emerging markets, the global factors are poor predictors of volatility in SA. However, SA's comovement with global volatility increases sharply in response to emerging market crises in Asia (1997-8) and Russia (1998). The global factors are also important determinants of domestic volatility during the latter stages of the US subprime crisis (2007-8). Chapter 5 proposes the factor-augmented VAR as a parsimonious model for the transmission of foreign volatility shocks to SA equities. We compare international volatility transmission resulting from crises in Asia (1997-8) and the US (2007-8). Although the US crisis has a larger impact on the world equity market, the Asian shock leads to more dramatic increases in volatility in emerging economies, including SA.

Thesis (M.M. (Finance & Investment)--University of the Witwatersrand, Faculty of Commerce, Law and Management, Wits Business School, 2017 / The South African economy is built on the richness of mineral resources found in most parts of the country. In 2013, Chamber of Mines reported that the country earned about R 2.4 trillion from the export market over the past 10 years. However, the industry has also shown signs of financial ill health in recent years. This study examines the factors affecting the financial performance (return on capital invested, return on asset and stock price return) of mining companies in South Africa with a particular focus on employee related factors (number of employees, wage bill and safest statistics). The study examines 24 publicly listed companies over a 6 year period using panel data analysis. The results show that lost time injury rate, number of fatalities are significant variables in explaining the changes in financial performance. Labour indicators such as number of employees, lost time injury rate and wages have a negative relationship with all financial indicators. / GR2018

A research report submitted to the Faculty of Commerce, Law and Management, University of the Witwatersrand, Johannesburg, In partial fulfilment of the requirements for the degree of Master of Management (Finance and Investment Management), 2016 / The relationship between real economic activity and stock market performance is one that has been extensively researched throughout many decades, across many economies. Many issues and debates have stemmed involving this relationship, with the major ones including those of the significance of the relationship, nature of the relationship as well as causality and direction of causality within the relationship. This research paper examines this relationship within the South African context, comparing the pre and post 2008 global financial crisis periods. Results both in support of and contrary to theory were found as real economic activity had an immediate postitive response to shocks imposed on the stock index, whilst the stock index had an immediate negative response to shocks imposed on real economic activity. Through the use of granger causality testing, no causality was found in either direction. Furthermore, no major differences were noted between the pre and post crisis periods. / GR2018

Thesis (M.M. (Finance & Investment)--University of the Witwatersrand, Faculty of Commerce, Law and Management, Wits Business School, 2017 / The study examined the relationship between oil price shocks, volatilities and stock indices in the African emerging markets. The ARDL and Bivariate BEKK GARCH models are used in this study. The countries examined are Botswana, Egypt, Mauritius, Morocco, Namibia, Nigeria, South Africa, Tanzania, Kenya, Ghana, Tunisia, and the MSCI’s World Index. The study shows a bidirectional relationship between oil price shocks for Nigeria and the MSCI, but unidirectional flow from oil price shocks to Botswana, Egypt, Mauritius, Morocco, Namibia, South Africa, Tanzania, Kenya, Ghana, and Tunisia. In addition, there is evidence of unidirectional volatility spill over from oil returns to Botswana, Namibia, Tanzania, Mauritius and Kenyan, Nigeria, Tanzania, Kenya and Ghana. Finally, the study found bidirectional volatility between oil and index returns in MSCI, South Africa, and Tunisia. / MT2017

A research report presented in partial fulfilment (50%) of the requirements for the degree of Master of Commerce in Business Economics (Finance) in the School of Economic and Business Sciences at the University of Witwatersrand, Johannesburg, 6 October 2017 / This study tests the efficacy of the liquidity variables of Liu (2006) in determining the existence of a liquidity premium on the South African market and finds evidence of a significant liquidity effect. This factor is determined to be robust and to proxy for a different underlying effect than the Fama-French (1992) effects and the market risk premium. The analysis is performed through portfolio sorts and tests for difference of portfolio means, as well as both a univariate and multivariate regression analysis. The sample period covers 16 years from 2000 to 2015. The relationship between size and liquidity is clear, however liquidity is found to be separate from the size effect. This study recommends the use of a liquidity-augmented model for the analysis of asset returns in South Africa. / GR2018

A research report submitted to the Faculty of Commerce, Law and Management, University of the Witwatersrand in partial fulfilment of the requirements for the degree of Master of Commerce in Finance. Johannesburg, South Africa March 2016 / The study examined whether: share repurchase events and changes in dividends were good predictors of future changes in earnings. The research also investigated how the South African market reacted to share repurchase events in the short-run. Using INET BFA, data for 226 dividend paying companies and 55 share repurchasing companies, trading on the JSE during the period 2003 to 2013, was collected. Dividend theory suggests that changes in dividends convey information content about the future earnings of the firm. After testing this theory, limited support was found for this notion. Firms that had increased dividends at (T0) showed significant earnings increases in that year. Nonetheless, some of the dividend increasing firms showed no subsequent unexpected earnings growth at (T1) and (T2). While the size of the dividend increase had a strong positive relationship with current earnings; it failed to predict future earnings with any consistency. Firms that had cut dividends at (T0) experienced a reduction in earnings in that year but showed increases in earnings at (T1). However, consistent with Lintner‘s (1956) model on dividend policy, firms that had increased their dividends were less likely to experience a reduction in earnings, as opposed to the no-change or dividend decrease groups. A linear regression model was employed in testing whether share repurchases were useful in predicting changes in future earnings. According to the results reported in the regression model, share repurchases are a good predictor of future changes in earnings. The study at hand then went on to explore how the South African market reacted to share repurchases. Through the utilisation of the Market Model-Event Study Methodology (with an event window of 41 days, 20 days prior and 20 days post the event), the findings of the report indicated that the South African market reacted positively to share repurchases. This was evidenced through positive: share price returns, abnormal returns and average abnormal returns, post the event. Nonetheless, cumulative average abnormal returns remained negative in the short-run. In addition, the results showed that firms engage in share repurchase activities in order to signal that the stock is undervalued. There was an observable trend of declining share prices before the share repurchase event. A few recommendations were proposed following the results obtained. Dividends are unable to predict changes in earnings. Therefore, a dividend cut, is not an indication that a company‘s earnings will decrease in the future or that the managers of that company foresee a decline in future earnings. From a share repurchase point of view, managers of JSE listed companies should not only focus on the short-term benefits of share repurchase events. These benefits are generally short lived as shares do return to their falling state, however authors such as Wesson, Muller and Ward (2014) have shown that the benefits of share repurchase events can also be observed in the long- run, A further point to note for both investors and managers of JSE listed companies is that share repurchases are a good predictor of future earnings. Therefore, it is very confusing for investors when a company announces a share repurchase event but does not follow through with it. / MT2017