Stock portfolio structure of individual investors infers future trading behavior

Although the understanding of and motivation behind individual trading behavior is an important puzzle in finance, little is known about the connection between an investor's portfolio structure and her trading behavior in practice. In this paper, we investigate the relation between what stocks investors hold, and what stocks they buy, and show that investors with similar portfolio structures to a great extent trade in a similar way. With data from the central register of shareholdings in Sweden, we model the market in a similarity network, by considering investors as nodes, connected with links representing portfolio similarity. From the network, we find groups of investors that not only identify different investment strategies, but also represent groups of individual investors trading in a similar way. These findings suggest that the stock portfolios of investors hold meaningful information, which could be used to earn a better understanding of stock market dynamics.Comment: 9 pages, 4 figures, 1 tabl

Shifting Spatialities of Power: The Case of Australasian Aviation

This paper explores how different modalities, spatialities and scales of power operate in a geopolitical context. By tracing the dynamic and shifting economic geographies of state and firm power in the events leading up to the collapse of a major Australian firm, Ansett Airlines, it reveals the difference that place and position make to the creation and use of power. The paper stresses agents’ relational positioning, their ‘places’ in multiple networks of association and the ways in which their past actions and visions of the future condition their strategic options. The paper contextualises the workings of power and explores how power relationships are re-configured in specific contested events. It concludes that power cannot be separated from the spatial and temporal dimensions of actual contexts, from actor’s positions in contexts, or from their strategic objective

Opinion Dynamics and Communication Networks

This paper examines the interplay of opinion exchange dynamics and communication network formation. An opinion formation procedure is introduced which is based on an abstract representation of opinions as $k$--dimensional bit--strings. Individuals interact if the difference in the opinion strings is below a defined similarity threshold $d_I$. Depending on $d_I$, different behaviour of the population is observed: low values result in a state of highly fragmented opinions and higher values yield consensus. The first contribution of this research is to identify the values of parameters $d_I$ and $k$, such that the transition between fragmented opinions and homogeneity takes place. Then, we look at this transition from two perspectives: first by studying the group size distribution and second by analysing the communication network that is formed by the interactions that take place during the simulation. The emerging networks are classified by statistical means and we find that non--trivial social structures emerge from simple rules for individual communication. Generating networks allows to compare model outcomes with real--world communication patterns.Comment: 14 pages 6 figure

The impact of hub hierarchy and market competition on airfare pricing in US hub-to-hub markets

Over the past years, full-service carriers in Europe have deployed multi-hub-and-spoke systems by joining alliances to exploit network economies. The concentration of flights on a small group of airports leads to the emergence of ‘fortress hubs’ and subsequently creates hub-to-hub markets in Europe reminiscent of the US aviation market. This paper explores the factors influencing the pricing behaviour of full-service carriers in European hub-to-hub markets. Drawing on a 2009 dataset containing route and airfare information, we establish an econometric model to estimate the impact of route structure, alliances, and market concentration on the pricing of European full-service carriers in these markets. Three types of hubs (i.e., primary, secondary and tertiary hubs) are hereby identified to investigate the route structure within the hub-to-hub network. The stepwise regression results suggest that alliances on routes connecting two primary hubs, market share inequality and competition from low-cost carriers influence average airfares of full-service carriers in the European hub-to-hub markets

Dynamic structure of stock communities: A comparative study between stock returns and turnover rates

The detection of community structure in stock market is of theoretical and practical significance for the study of financial dynamics and portfolio risk estimation. We here study the community structures in Chinese stock markets from the aspects of both price returns and turnover rates, by using a combination of the PMFG and infomap methods based on a distance matrix. We find that a few of the largest communities are composed of certain specific industry or conceptional sectors and the correlation inside a sector is generally larger than the correlation between different sectors. In comparison with returns, the community structure for turnover rates is more complex and the sector effect is relatively weaker. The financial dynamics is further studied by analyzing the community structures over five sub-periods. Sectors like banks, real estate, health care and New Shanghai take turns to compose a few of the largest communities for both returns and turnover rates in different sub-periods. Several specific sectors appear in the communities with different rank orders for the two time series even in the same sub-period. A comparison between the evolution of prices and turnover rates of stocks from these sectors is conducted to better understand their differences. We find that stock prices only had large changes around some important events while turnover rates surged after each of these events relevant to specific sectors, which may offer a possible explanation for the complexity of stock communities for turnover rates

Backbone of complex networks of corporations: The flow of control

We present a methodology to extract the backbone of complex networks based on the weight and direction of links, as well as on nontopological properties of nodes. We show how the methodology can be applied in general to networks in which mass or energy is flowing along the links. In particular, the procedure enables us to address important questions in economics, namely, how control and wealth are structured and concentrated across national markets. We report on the first cross-country investigation of ownership networks, focusing on the stock markets of 48 countries around the world. On the one hand, our analysis confirms results expected on the basis of the literature on corporate control, namely, that in Anglo-Saxon countries control tends to be dispersed among numerous shareholders. On the other hand, it also reveals that in the same countries, control is found to be highly concentrated at the global level, namely, lying in the hands of very few important shareholders. Interestingly, the exact opposite is observed for European countries. These results have previously not been reported as they are not observable without the kind of network analysis developed here.Comment: 24 pages, 12 figures, 2nd version (text made more concise and readable, results unchanged

Contradictions in adult education structures and policies in Austria: their interrelation with the professional development of educators

This article analyses the structural influences on the professional development of adult educators and their relation to education policy using Austria as a fairly average example of the diversity in European adult education. The position of adult education is first analysed in the course of the development of a lifelong learning strategy, showing a set of basic contradictions that are institutionally embedded in educational practices and policies. The consequences of these constellations for professional development in adult education are then examined, and a policy analysis undertaken based on institutional theory and using literature, documents and secondary data. This analysis shows that the contradictions in the institutional structures and policies inhibit both the development of a lifelong learning strategy as well as the professional development of adult educators. The competence development and quality assurance approaches adopted in Europe contribute only very modestly to the development of adult education in Austria. (DIPF/orig.