Can a multilateral negotiating process—that is, cooperation between many states in a single forum—successfully reform the network of bilateral tax treaties that currently makes up the bulk of international tax law? The BEPS Project aims to be the first major push for a multilateral tax process since the creation of the OECD’s Model Tax Convention in the 1960s. Through BEPS, the OECD and 130-plus countries are in final negotiations to implement Pillar One and Two, which will: (1) create a new taxing right for “market jurisdiction” countries on the profit of international companies that do business there without a physical presence; and (2) implement a top-up tax levied against companies that offshore profits from intangible assets in low-tax jurisdictions. To predict whether the multilateral reform effort will be successful, it is important to examine the nature of the multilateral negotiating process itself, because every negotiation is shaped by its context.  But this context is not static—rather, the nature of tax multilateralism varies depending on certain global conditions. Sometimes, it is a hierarchical process, dominated by powerful countries operating in a closed-club of developed states spearheading the effort, while weaker countries must tag along and accept the eventual outcome. Alternatively, multilateralism may be egalitarian and inclusive, with many countries—strong and weak alike—contributing to the debate, accepting tradeoffs, and endorsing the outcome. In this thesis, I demonstrate that the nature of tax multilateralism has changed from the former model to the latter by comparing the negotiation of the OECD Model Tax Conventions with the Pillars Negotiation. I begin by identifying several factors that influence the nature of tax multilateralism: first, the distribution of global power among states; and second, the level of integration of the global economy. In an international system where power is concentrated in a few states, and the international economy is fragmented (i.e., the conditions of the 20th Century), multilateralism tends to be hierarchical and exclusive. However, when power is diffused and the global economy is integrated, (the conditions of the 21st Century), then multilateralism is egalitarian and inclusive. In such a context, international tax issues—like base erosion and profit-shifting—are so vast and complex that no state, acting alone or in a small group, could deal with them. The thesis thus concludes that the nature of tax multilateralism has changed, because in modern negotiations, powerful states are both less capable of dominating other states in the negotiating process and are highly dependent on a successful outcome that creates global consensus.

The aim of this study was to assess the feasibility of constructing optimal portfolios using the Johannesburg Securities Exchange tradable sector indices. Three indices were employed, namely Financials, Industrials and Resources and were benchmarked against the JSE All Share Index for the period January 2007 to December 2017. The period was split into three, namely before the 2007-2009 global financial crises, during the global financial crises and after the global financial crises. The Markowitz’s mean-variance optimisation framework was employed for the construction of global mean variance portfolios. The results of this study showed that it was feasible to construct mean-variance efficient portfolios using tradable sector indices from the Johannesburg Securities Exchange. It was also established that, on the other hand, global mean variance portfolios constructed in this study, outperformed the benchmark index in a bullish market in terms of the risk-return combinations. On the other hand, in bear markets, the global mean variance portfolios were observed to perform better than the benchmark index in terms of risk. Further, the results of the study showed that portfolios constructed from the three tradable indices yielded diversification benefits despite their positive correlation with each other. The results of the study corroborate the findings by other scholars that the mean-variance optimisation framework is effective in the construction of optimal portfolios using the Johannesburg Securities Exchange. The study also demonstrated that Markowitz’s mean-variance framework could be applied by investors faced with a plethora of investment choices to construct efficient portfolios utilising the Johannesburg Securities Exchange tradable sector indices to achieve returns commensurate with their risk preferences. / Business Management / M. Com. (Business Management)

Despite the fact that illiquid assets pose several difficulties regarding portfolio allocation problems for investors, more investors are increasing their allocation towards them. Alternative assets are characterized as being harder to value and trade because of their illiquidity which raises the question of how they should be managed from an allocation optimization perspective. In an attempt to demystify the illiquidity conundrum, shadow allocations are attached to the classical mean-variance framework to account for liquidity activities. The framework is further improved by replacing the variance for the coherent risk measure conditional value at risk (CVaR). This framework is then used to first stress test and optimize a theoretical portfolio and then analyze real-world data in a case study. The investors’ liquidity preferences are based on common institutional investors such as Foundations & Charities, Pension Funds, and Unions. The theoretical results support previous findings of the shadow allocations framework and decrease the allocation towards illiquid assets, while the results of the case study do not support the shadow allocations framework. / Trots det faktum att illikvida tillgångar medför flera svårigheter när det gäller portföljallokeringsproblem för investerare, så ökar allt fler investerare sin allokering mot dem. Alternativa tillgångar kännetecknas av att de är svårare att värdera och handla på grund av sin illikviditet, vilket väcker frågan om hur de ska hanteras ur ett allokeringsoptimeringsperspektiv. I ett försök att avmystifiera illikviditetsproblemet adderas skuggallokeringar till det klassiska ramverket för modern portföljteori för att ta hänsyn till likviditetsaktiviteter. Ramverket förbättras ytterligare genom att ersätta variansen mot det koherenta riskmåttet CVaR. Detta ramverk används sedan för att först stresstesta och optimera en teoretisk portfölj, och sedan analysera verkliga data i en fallstudie. Investerarnas likviditetspreferenser baseras på vanliga institutionella investerare såsom stiftelser & välgörenhetsorganisationer, pensionsfonder samt fackföreningar. De teoretiska resultaten stödjer tidigare forskning om ramverket för skuggallokeringer och sänker allokeringen mot illikvida tillgångar, samtidigt som resultaten från fallstudien inte stödjer ramverket för skuggallokeringar.

Introduction: No Fixed-Dose Combination (FDC) formulations currently exist for pediatric tuberculosis (TB) treatment. Earlier work implemented, in the software NONMEM, a rational method for optimizing design and individualization of pediatric anti-TB FDC formulations based on patient body weight, but issues with parameter estimation, dosage strata heterogeneity and representative pharmacokinetics remained. Aim: To further develop the rational model-based methodology aiding the selection of appropriate FDC formulation designs and dosage regimens, in pediatric TB treatment. Materials and Methods: Optimization of the method with respect to the estimation of body weight breakpoints was sought. Heterogeneity of dosage groups with respect to treatment efficiency was sought to be improved. Recently published pediatric pharmacokinetic parameters were implemented and the model translated to MATLAB, where also the performance was evaluated by stochastic estimation and graphical visualization. Results: A logistic function was found better suited as an approximation of breakpoints. None of the estimation methods implemented in NONMEM were more suitable than the originally used FO method. Homogenization of dosage group treatment efficiency could not be solved. MATLAB translation was successful but required stochastic estimations and highlighted high densities of local minima. Representative pharmacokinetics were successfully implemented. Conclusions: NONMEM was found suboptimal for the task due to problems with discontinuities and heterogeneity, but a stepwise method with representative pharmacokinetics were successfully implemented. MATLAB showed more promise in the search for a method also addressing the heterogeneity issue.