Ex-Dividend Day Returns when Dividend and Capital Gains are Taxed at the Same Rate

Due to the overwhelming international evidence that stock prices drop by less than the dividend paid on ex-dividend days, the ex-dividend day anomaly is considered a stylized fact. Two main approaches have emerged to explain this empirical regularity: the tax-clientele hypothesis and the microstructure of financial markets. Although the most widely accepted explanation for this fact relies on taxes, the ex-dividend day anomaly has been reported even in countries where neither dividends nor capital gains are taxed. The 2006 tax reform in Spain established the same tax rate for dividends and capital gains. This paper investigates stock returns on ex-dividend days in the Spanish stock market after the 2006 tax reform using a random coefficient model. Contrary to previous research, we do not observe an ex-dividend day anomaly. Unlike previous investigations, which are mostly concerned with suggesting explanations as to why this anomaly has occurred, we are in the somewhat strange position of discussing why this anomaly has not occurred. Our findings are robust across companies and stock dividend yields, thus supporting a tax--based explanation for the ex-dividend day anomaly.

Factors influencing zooplankton size structure at contrasting temperatures in coastal shallow lakes: Implications for effects of climate change

We assessed the importance of temperature, salinity, and predation for the size structure of zooplankton and provided insight into the future ecological structure and function of shallow lakes in a warmer climate. Artificial plants were introduced in eight comparable coastal shallow brackish lakes located at two contrasting temperatures: cold-temperate and Mediterranean climate region. Zooplankton, fish, and macroinvertebrates were sampled within the plants and at open-water habitats. The fish communities of these brackish lakes were characterized by small-sized individuals, highly associated with submerged plants. Overall, higher densities of small planktivorous fish were recorded in the Mediterranean compared to the cold-temperate region, likely reflecting temperature-related differences as have been observed in freshwater lakes. Our results suggest that fish predation is the major control of zooplankton size structure in brackish lakes, since fish density was related to a decrease in mean body size and density of zooplankton and this was reflected in a unimodal shaped biomass-sizespectrum with dominance of small sizes and low size diversity. Salinity might play a more indirect role by shaping zooplankton communities toward more salt-tolerant species. In a global-warming perspective, these results suggest that changes in the trophic structure of shallow lakes in temperate regions might be expected as a result of the warmer temperatures and the potentially associated increases in salinity. The decrease in the density of largebodied zooplankton might reduce the grazing on phytoplankton and thus the chances of maintaining the clear water state in these ecosystems

Finnish stock market reaction to quarterly earnings announcements

This thesis examines the stock market reactions to quarterly earnings announcements. The study covers the OMX Helsinki 25 index companies for the years 2007–2010. The stock market response to quarterly earnings announcements is tested by employing the event study –methodology and daily stock returns of Finnish listed companies. The thesis provides evidence that stock prices react to earnings announcements that exceed or fall below analyst forecasts. The most liquid stocks earn higher returns around positive earnings news than less traded stocks, which supports the evidence from previous studies. This thesis finds evidence for the authorization to sell stocks short reducing the post–earnings announcement drift induced by negative earnings news. In addition, the market’s reaction to earnings announcements seems to quicken during economic turmoil.

Insiders´ views as a predictor of stock performance : can insider trading be used to predict stock performance on the United States stock market?

This thesis studies the possibility of using information on insiders’ transactions to forecast future stock returns after the implementation of Sarbanes Oxley Act in July 2003. Insider transactions between July 2003 and August 2009 are analysed with regression tests to identify the relationships between insiders’ transactions and future stock returns. This analysis is complemented with rudimentary bootstrapping procedures to verify the robustness of the findings. The underlying assumption of the thesis is that insiders constantly receive pieces of information that indicate future performance of the company. They may not be allowed to trade on large and tangible pieces of information but they can trade on accumulation of smaller, intangible pieces of information. Based on the analysis in the thesis insiders’ profits were found not to differ from the returns from broad stock index. However, their individual transactions were found to be linked to future stock returns. The initial model was found to be unstable but some of the predictive power could be sacrificed to achieve greater stability. Even after sacrificing some predictive power the relationship was significant enough to allow external investors to achieve abnormal profits after transaction costs and taxes. The thesis does not go into great detail about timing of transactions. Delay in publishing insiders’ transactions is not taken into account in the calculations and the closed windows are not studied in detail. The potential effects of these phenomena are looked into and they do not cause great changes in the findings. Additionally the remuneration policy of an insider or a company is not taken into account even though it most likely affects the trading patterns of insiders. Even with the limitations the findings offer promising opportunities for investors to improve their investment processes by incorporating additional information from insiders’ transaction into their decisions. The findings also raise questions on how insider trading should be regulated. Insiders achieve greater returns than other investors based on superior information. On the other hand, more efficient information transfer could warrant more lenient regulation. The fact that insiders’ returns are dominated by the large investment stake they maintain all the time in their own companies also speaks for more leniency. As Sarbanes Oxley Act considerably modified the insider trading landscape, this analysis provides information that has not been available before. The thesis also constitutes a thorough analysis of insider trading phenomenon which has previously been somewhat separated into several studies.

Irtoamispäivän kurssilaskusuhteet, epänormaalit tuotot sekä epänormaalit kaupankäyntivolyymit vuosina 2005-2013

Tutkielman tavoitteena on tutkia osingon irtoamispäivän tapahtumia OMX Helsinki 25:n yrityksillä vuosina 2005–2013. Vallitsevan käsityksen mukaan osakkeen hinta laskee irtoamispäivänä osingon verran +/- markkinoiden yleisestä hintamuutoksesta johtuva nousu/lasku. Käsitystä on pyritty murtamaan vuosien saatossa neljän eri teorian avulla, jotka ovat veroasiakaskuntateoria, lyhytaikaisen vaihdon hypoteesi, dynaaminen malli sekä mikrorakenneteoria. Osingon irtoamispäivää tarkastellaan kolmen eri tutkimuksen avulla ja saatuja tuloksia verrataan teoriaan sekä aikaisempiin löydöksiin. Tutkimusosuudet ovat kurssilaskusuhteet, epänormaalit tuotot sekä epänormaalit kaupankäyntivolyymit. Kurssilaskusuhdetta tarkastellaan vertaamalla cum-päivän ja irtoamispäivän osakkeiden hintojen erotusta maksetun osingon määrään. Epänormaaleja tuottoja ja epänormaaleja kaupankäyntivolyymejä tarkastellaan tapahtumatutkimus-menetelmällä viisi päivää ennen ja viisi päivää jälkeen osingon irtoamisen. Kurssilaskusuhteet olivat eri tavoilla laskettuina 77 – 94 %. Irtoamispäivän ympärillä oli havaittavissa 1,5 %:n negatiivisia epänormaaleja tuottoja. Epänormaalit kaupankäyntivolyymit kasvoivat tasaisesti lähestyttäessä irtoamispäivää ja olivat voimakkaimmillaan irtoamispäivänä. Irtoamispäivän jälkeen kaupankäyntivolyymit palautuivat hiljalleen normaalille tasolle. Tulokset vastaavat aikaisempia löydöksiä kurssilaskusuhteita ja epänormaaleja volyymejä tarkasteltaessa, mutta eroavat epänormaaleissa tuotoissa.

Determination of myocardial infarction size in rats by echocardiography and tetrazolium staining: correlation, agreements, and simplifications

Triphenyltetrazolium chloride (TTC) staining and echocardiography (ECHO) are methods used to determine experimental myocardial infarction (MI) size, whose practical applicability should be expanded. Our objectives were to analyze the accuracy of ECHO in determining infarction size in rats during the first days following coronary occlusion and to test whether a simplified single measurement by TTC correctly indicates MI size, as determined by the average value for multiple slices. Infarction was induced in female Wistar rats by coronary artery occlusion and MI size analysis was performed after the acute (7th day) and chronic periods (after 4 weeks) by ECHO matched with TTC. ECHO and TTC showed similar values of MI size (% of left ventricle perimeter) in acute (ECHO: 33 ± 11, TTC: 35 ± 14) and chronic (ECHO: 38 ± 14, TTC: 39 ± 13 periods), and also presented an excellent correlation (r = 0.92, P < 0.001). Although measurements from different heart planes showed discrepancies, a single measurement acquired from the mid-ventricular level by TTC was a good estimate of MI size calculated by the average of multiple planes, with minimal disagreement (Bland-Altman test with mean ratio bias of 0.99 ± 0.07) and close to an ideal correlation (r = 0.99, P < 0.001). In the present study, ECHO was confirmed as a useful method for the determination of MI size even in the acute phase. Also, the single measure of a mid-ventricular section proposed as a simplification of the TTC method is a satisfactory prediction of average MI extension.

Return and Volatility spillovers among stock and Foreign Exchange Markets: Empirical Evidence from selected African Markets

Return and volatility dynamics in financial markets across the world have recently become important for the purpose of asset pricing, portfolio allocation and risk management. However, volatility, which come about as a result of the actions of market participants can help adapt to different situations and perform when it really matters. With recent development and liberalization among financial markets in emerging and frontier markets, the need for how the equity and foreign exchange markets interact and the extent to which return and volatility spillover are spread across countries is of importance to investors and policy makers at large. Financial markets in Africa have received attention leading to investors diversifying into them in times of crisis and contagion effects in developed countries. Regardless of the benefits these markets may offer, investors must be wary of issues such as thin trading, volatility that exists in the equity and currency markets and its related fluctuations. The study employs a VAR-GARCH BEKK model to study the return and volatility dynamics between the stock and foreign exchange sectors and among the equity markets of Egypt, Kenya, Nigeria, South Africa and Tunisia. The main findings suggest a higher dependence of own return in the stock markets and a one way return spillover from the currencies to the equity markets except for South Africa which has a weaker interrelation among the two markets. There is a relatively limited integration among the equity markets. Return and volatility spillover is mostly uni-directional except for a bi-directional relationship between the equity markets of Egypt and Tunisia. The study implication still proves a benefit for portfolio managers diversifying in these African equity markets, since they are independent of each other and may not be highly affected by the influx of negative news from elsewhere. However, there is the need to be wary of return and volatility spillover between the equity and currency markets, hence devising better hedging strategies to curb them.

A performance analysis of conventional and fundamental exchange traded funds: ETFs and their risk-return characteristics in relation to building institutional investor’s passive portfolio

An exchange traded fund (ETF) is a financial instrument that tracks some predetermined index. Since their initial establishment in 1993, ETFs have grown in importance in the field of passive investing. The main reason for the growth of the ETF industry is that ETFs combine benefits of stock investing and mutual fund investing. Although ETFs resemble mutual funds in many ways, also many differences occur. In addition, ETFs not only differ from mutual funds but also differ among each other. ETFs can be divided into two categories, i.e. market capitalisation ETFs and fundamental (or strategic) ETFs, and further into subcategories depending on their fundament basis. ETFs are a useful tool for diversification especially for a long-term investor. Although the economic importance of ETFs has risen drastically during the past 25 years, the differences and risk-return characteristics of fundamental ETFs have yet been rather unstudied area. In effect, no previous research on market capitalisation and fundamental ETFs was found during the research process. For its part, this thesis seeks to fill this research gap. The studied data consist of 50 market capitalisation ETFs and 50 fundamental ETFs. The fundaments, on which the indices that the fundamental ETFs track, were not limited nor segregated into subsections. The two types of ETFs were studied at an aggregate level as two different research groups. The dataset ranges from June 2006 to December 2014 with 103 monthly observations. The data was gathered using Bloomberg Terminal. The analysis was conducted as an econometric performance analysis. In addition to other econometric measures, the methods that were used in the performance analysis included modified Value-at-Risk, modified Sharpe ratio and Treynor ratio. The results supported the hypothesis that passive market capitalisation ETFs outperform active fundamental ETFs in terms of risk-adjusted returns, though the difference is rather small. Nevertheless, when taking into account the higher overall trading costs of the fundamental ETFs, the underperformance gap widens. According to the research results, market capitalisation ETFs are a recommendable diversification instrument for a long-term investor. In addition to better risk-adjusted returns, passive ETFs are more transparent and the bases of their underlying indices are simpler than those of fundamental ETFs. ETFs are still a young financial innovation and hence data is scarcely available. On future research, it would be valuable to research the differences in risk-adjusted returns also between the subsections of fundamental ETFs.

The impact of companies’ demergers to the stock prices: a Finnish perspective

Tässä kauppatieteiden kandidaatintyössä tutkittiin millaisia vaikutuksia julkisesti noteerattujen yhtiöiden osakekurssissa tapahtuu, kun jo valmiiksi Helsingin pörssissä listattu yritys jakautuu kahdeksi uudeksi pörssiyritykseksi. Molempien yrityksien osakkeita voi tämän jakautumisen jälkeen vapaasti ostaa tai myydä. Aikaisempi tutkimus on pääsääntöisesti keskittynyt Yhdysvaltojen markkinoille ja näiden tutkimusten tuloksien perusteella on monessa tapauksessa havautta, että on mahdollista saavuttaa ylinormaaleja tuottoja, kun pörssiyritys jakautuu kahdeksi uudeksi pörssiyritykseksi. Tässä analyysissä jakautumiset ajallisesti tapahtuivat vuosien 1994 ja 2013 välisenä aikana Suomessa ja näitä jakautumia oli yhteensä 16 kappaletta. Tutkimuksessa on hyödynnetty tilastollisten menetelmien analyysiä sekä CAP-mallia, jotta voitaisiin löytää vastauksia seuraaviin kysymyksiin: Vaikuttaako pörssiyrityksen jakautuminen kahdeksi pörssiyritykseksi alkuperäisen yhtiön ja uuden yhtiön osakekursseihin? Onko vaikutus positiivinen, negatiivinen vai onko jakautumisella mitään havaittavaa vaikutusta? Tämän tutkimuksen tulokset antavat uutta tietoa tutkijoille, analyytikoille, opettajille, opiskelijoille, yrityksille ja yritysten johdolle sekä erityisesti sijoittajille. Tulosten mukaan on nähtävissä monia vaikutuksia osakekursseissa, kun pörssiyritys jakautuu. Vaikutus näyttää kuitenkin olevan jossain määrin yritys-riippuvainen. Kun sijoitetaan oikeaan aikaan, on monia jakautuvia yrityksiä, jotka antavat hyvän tuoton keskimäärin, mutta kuten tavallista ja tyypillistä osakemarkkinoille, on myös jakautuvia yhtiöitä, jotka antavat negatiivisia tuottoja tai tuotot ovat nollassa

Size regulation of double and half embryos in the mice musculus

Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.

Essays in macro finance and monetary economics

Les questions abordées dans les deux premiers articles de ma thèse cherchent à comprendre les facteurs économiques qui affectent la structure à terme des taux d'intérêt et la prime de risque. Je construis des modèles non linéaires d'équilibre général en y intégrant des obligations de différentes échéances. Spécifiquement, le premier article a pour objectif de comprendre la relation entre les facteurs macroéconomiques et le niveau de prime de risque dans un cadre Néo-keynésien d'équilibre général avec incertitude. L'incertitude dans le modèle provient de trois sources : les chocs de productivité, les chocs monétaires et les chocs de préférences. Le modèle comporte deux types de rigidités réelles à savoir la formation des habitudes dans les préférences et les coûts d'ajustement du stock de capital. Le modèle est résolu par la méthode des perturbations à l'ordre deux et calibré à l'économie américaine. Puisque la prime de risque est par nature une compensation pour le risque, l'approximation d'ordre deux implique que la prime de risque est une combinaison linéaire des volatilités des trois chocs. Les résultats montrent qu'avec les paramètres calibrés, les chocs réels (productivité et préférences) jouent un rôle plus important dans la détermination du niveau de la prime de risque relativement aux chocs monétaires. Je montre que contrairement aux travaux précédents (dans lesquels le capital de production est fixe), l'effet du paramètre de la formation des habitudes sur la prime de risque dépend du degré des coûts d'ajustement du capital. Lorsque les coûts d'ajustement du capital sont élevés au point que le stock de capital est fixe à l'équilibre, une augmentation du paramètre de formation des habitudes entraine une augmentation de la prime de risque. Par contre, lorsque les agents peuvent librement ajuster le stock de capital sans coûts, l'effet du paramètre de la formation des habitudes sur la prime de risque est négligeable. Ce résultat s'explique par le fait que lorsque le stock de capital peut être ajusté sans coûts, cela ouvre un canal additionnel de lissage de consommation pour les agents. Par conséquent, l'effet de la formation des habitudes sur la prime de risque est amoindri. En outre, les résultats montrent que la façon dont la banque centrale conduit sa politique monétaire a un effet sur la prime de risque. Plus la banque centrale est agressive vis-à-vis de l'inflation, plus la prime de risque diminue et vice versa. Cela est due au fait que lorsque la banque centrale combat l'inflation cela entraine une baisse de la variance de l'inflation. Par suite, la prime de risque due au risque d'inflation diminue. Dans le deuxième article, je fais une extension du premier article en utilisant des préférences récursives de type Epstein -- Zin et en permettant aux volatilités conditionnelles des chocs de varier avec le temps. L'emploi de ce cadre est motivé par deux raisons. D'abord des études récentes (Doh, 2010, Rudebusch and Swanson, 2012) ont montré que ces préférences sont appropriées pour l'analyse du prix des actifs dans les modèles d'équilibre général. Ensuite, l'hétéroscedasticité est une caractéristique courante des données économiques et financières. Cela implique que contrairement au premier article, l'incertitude varie dans le temps. Le cadre dans cet article est donc plus général et plus réaliste que celui du premier article. L'objectif principal de cet article est d'examiner l'impact des chocs de volatilités conditionnelles sur le niveau et la dynamique des taux d'intérêt et de la prime de risque. Puisque la prime de risque est constante a l'approximation d'ordre deux, le modèle est résolu par la méthode des perturbations avec une approximation d'ordre trois. Ainsi on obtient une prime de risque qui varie dans le temps. L'avantage d'introduire des chocs de volatilités conditionnelles est que cela induit des variables d'état supplémentaires qui apportent une contribution additionnelle à la dynamique de la prime de risque. Je montre que l'approximation d'ordre trois implique que les primes de risque ont une représentation de type ARCH-M (Autoregressive Conditional Heteroscedasticty in Mean) comme celui introduit par Engle, Lilien et Robins (1987). La différence est que dans ce modèle les paramètres sont structurels et les volatilités sont des volatilités conditionnelles de chocs économiques et non celles des variables elles-mêmes. J'estime les paramètres du modèle par la méthode des moments simulés (SMM) en utilisant des données de l'économie américaine. Les résultats de l'estimation montrent qu'il y a une évidence de volatilité stochastique dans les trois chocs. De plus, la contribution des volatilités conditionnelles des chocs au niveau et à la dynamique de la prime de risque est significative. En particulier, les effets des volatilités conditionnelles des chocs de productivité et de préférences sont significatifs. La volatilité conditionnelle du choc de productivité contribue positivement aux moyennes et aux écart-types des primes de risque. Ces contributions varient avec la maturité des bonds. La volatilité conditionnelle du choc de préférences quant à elle contribue négativement aux moyennes et positivement aux variances des primes de risque. Quant au choc de volatilité de la politique monétaire, son impact sur les primes de risque est négligeable. Le troisième article (coécrit avec Eric Schaling, Alain Kabundi, révisé et resoumis au journal of Economic Modelling) traite de l'hétérogénéité dans la formation des attentes d'inflation de divers groupes économiques et de leur impact sur la politique monétaire en Afrique du sud. La question principale est d'examiner si différents groupes d'agents économiques forment leurs attentes d'inflation de la même façon et s'ils perçoivent de la même façon la politique monétaire de la banque centrale (South African Reserve Bank). Ainsi on spécifie un modèle de prédiction d'inflation qui nous permet de tester l'arrimage des attentes d'inflation à la bande d'inflation cible (3% - 6%) de la banque centrale. Les données utilisées sont des données d'enquête réalisée par la banque centrale auprès de trois groupes d'agents : les analystes financiers, les firmes et les syndicats. On exploite donc la structure de panel des données pour tester l'hétérogénéité dans les attentes d'inflation et déduire leur perception de la politique monétaire. Les résultats montrent qu'il y a évidence d'hétérogénéité dans la manière dont les différents groupes forment leurs attentes. Les attentes des analystes financiers sont arrimées à la bande d'inflation cible alors que celles des firmes et des syndicats ne sont pas arrimées. En effet, les firmes et les syndicats accordent un poids significatif à l'inflation retardée d'une période et leurs prédictions varient avec l'inflation réalisée (retardée). Ce qui dénote un manque de crédibilité parfaite de la banque centrale au vu de ces agents.

Los conceptos de salud financiera, riesgo y epidemiología en los estados financieros de las compañías del sector de extracción de petróleo crudo y gas natural en Colombia

El presente proyecto tiene como objeto identificar cuáles son los conceptos de salud, enfermedad, epidemiología y riesgo aplicables a las empresas del sector de extracción de petróleo y gas natural en Colombia. Dado, el bajo nivel de predicción de los análisis financieros tradicionales y su insuficiencia, en términos de inversión y toma de decisiones a largo plazo, además de no considerar variables como el riesgo y las expectativas de futuro, surge la necesidad de abordar diferentes perspectivas y modelos integradores. Esta apreciación es pertinente dentro del sector de extracción de petróleo y gas natural, debido a la creciente inversión extranjera que ha reportado, US$2.862 millones en el 2010, cifra mayor a diez veces su valor en el año 2003. Así pues, se podrían desarrollar modelos multi-dimensional, con base en los conceptos de salud financiera, epidemiológicos y estadísticos. El termino de salud y su adopción en el sector empresarial, resulta útil y mantiene una coherencia conceptual, evidenciando una presencia de diferentes subsistemas o factores interactuantes e interconectados. Es necesario mencionar también, que un modelo multidimensional (multi-stage) debe tener en cuenta el riesgo y el análisis epidemiológico ha demostrado ser útil al momento de determinarlo e integrarlo en el sistema junto a otros conceptos, como la razón de riesgo y riesgo relativo. Esto se analizará mediante un estudio teórico-conceptual, que complementa un estudio previo, para contribuir al proyecto de finanzas corporativas de la línea de investigación en Gerencia.

Impacto de la venta de acciones en la salud financiera y el riesgo en los grupos financieros

Esta investigación tiene como objetivo general el análisis del impacto de la venta de acciones sobre la salud financiera y el riesgo en el grupo Aval. La necesidad por este estudio nace del interés por conocer los costos y beneficios que tienen las empresas a la hora de emitir acciones, siendo ésta última una práctica común en las últimas décadas. Algunas de las motivaciones relevantes para emitir acciones, son la financiación de nuevos proyectos de la empresa, el status que le pueda dar a la misma, una manera de hacer frente a la deuda, etc. Es importante conocer las implicaciones que tienen sobre la empresa la venta de acciones en términos de sus resultados, el impacto sobre los accionistas y sobre la misma sociedad. Esta investigación busca responder a la pregunta: ¿Cuál es el impacto de la venta de acciones sobre la salud financiera y el riesgo en los grupos financieros? Nos interesaremos por la revisión bibliográfica acerca de la salud financiera abordando autores que hablan de la misma desde el punto de vista de la posición de la empresa, refiriéndonos siempre a tres indicadores relevantes para el estudio y que son utilizados en la literatura para medir la salud financiera: liquidez, rentabilidad y endeudamiento. En la revisión de la literatura se ha encontrado una relación entre la salud financiera y el riesgo, por lo tanto buscaremos identificar cuál es el riesgo que afecta a las empresas cuando se emiten acciones centrándonos en tres tipos de riesgos financieros: riesgo de mercado, de interés y riesgo operacional; se ha escogido el grupo Aval para éste estudio ya que es uno de los grupos financieros más importantes en Colombia, con varios años de gestión y que actualmente realiza la práctica de emitir acciones.

Factors influencing zooplankton size structure at contrasting temperatures in coastal shallow lakes: Implications for effects of climate change

We assessed the importance of temperature, salinity, and predation for the size structure of zooplankton and provided insight into the future ecological structure and function of shallow lakes in a warmer climate. Artificial plants were introduced in eight comparable coastal shallow brackish lakes located at two contrasting temperatures: cold-temperate and Mediterranean climate region. Zooplankton, fish, and macroinvertebrates were sampled within the plants and at open-water habitats. The fish communities of these brackish lakes were characterized by small-sized individuals, highly associated with submerged plants. Overall, higher densities of small planktivorous fish were recorded in the Mediterranean compared to the cold-temperate region, likely reflecting temperature-related differences as have been observed in freshwater lakes. Our results suggest that fish predation is the major control of zooplankton size structure in brackish lakes, since fish density was related to a decrease in mean body size and density of zooplankton and this was reflected in a unimodal shaped biomass-size spectrum with dominance of small sizes and low size diversity. Salinity might play a more indirect role by shaping zooplankton communities toward more salt-tolerant species. In a global-warming perspective, these results suggest that changes in the trophic structure of shallow lakes in temperate regions might be expected as a result of the warmer temperatures and the potentially associated increases in salinity. The decrease in the density of largebodied zooplankton might reduce the grazing on phytoplankton and thus the chances of maintaining the clear water state in these ecosystems

Analysis of ochres from Clearwell Caves: the role of particle size in determining colour

Three ochre samples (A (orange-red in colour), B (red) and C (purple)) from Clearwell Caves, (Gloucestershire, UK) have been examined using an integrated analytical methodology based on the techniques of IR and diffuse reflectance UV-visible-NIR spectroscopy, X-ray diffraction, elemental analysis by ICP-AES and particle size analysis. It is shown that the chromophore in each case is haematite. The differences in colour may be accounted for by (i) different mineralogical and chemical composition in the case of the orange ochre, where hi,,her levels of dolomite and copper are seen and (ii) an unusual particle size distribution in the case of the purple ochre. When the purple ochre was ground to give the same particle size distribution as the red ochre then the colours of the two samples became indistinguishable. An analysis has now been completed of a range of ochre samples with colours from yellow to purple from the important site of Clearwell Caves. (C) 2004 Elsevier B.V. All rights reserved.