Lattice duality for families of K3K3 surfaces associated to transpose duality

The aim of this article is to show that the transpose-dual pairs in the sense of Ebeling-Ploog of singularities $(Z_{1,0},\, Z_{1,0})$, $(U_{1,0},\, U_{1,0})$, $(Q_{17},\, Z_{2,0})$, $(W_{1,0},\, W_{1,0})$ that are concluded to be polytope-dual by the author are actually lattice-dual.Comment: 16 pages,3 tables,to appear in manuscripta mathematic

The impact of changes in the FTSE 100 index

This paper examines both the long-term and short-term impact associated with changes in the constituents of the FTSE 100 Index. We find that stocks exhibit positive (negative) abnormal long-run performance following their inclusion in (deletion from) the index. There is also evidence of significant short-term cumulative abnormal returns around the event. The reversal of these price effects suggests that short-term buying (selling) pressure (possibly from index trackers) moves prices temporarily away from equilibrium. An analysis of stock liquidity implies speculators may trade in advance of the announcement, while index trackers trade between the announcement and event dates. Finally, the organisation of the FTSE 100 Index enables us to conduct an analysis of stocks that just avoid being relegated from (fail to be promoted to) the FTSE 100

A Change of Focus: Stock Market Classification in the UK

This paper examines the impact of a change of focus by a firm, as signified by stock market reclassification. It distinguishes between sector reclassifications that are motivated by information specific to a particular firm, and those that result from sector redefinitions and reorganisations. The direction of the price effects following reclassification depends significantly upon this distinction. Moreover, for firm-specific reclassifications, the negative price effect is greater where the firm has been underperforming its sector, suggesting that investors may be sceptical about the motives underlying a change of focus. Furthermore, a stock’s return comovement with the FTSE All-Share Index may be affected by it being reclassified into a new sector. This change in return comovement is consistent with the allocation of stocks into categories, as discussed by Barberis and Shleifer (2003). Reclassification can induce common factors in the returns to stocks in an index without there being any change in these stocks’ fundamental cash flows

The Information Contained in The Exercise of Executive Stock Options

This paper investigates the use by insiders of private information in their decision to exercise executive stock options. It is the first to categorise the exercise of an executive stock option by the proportion of stock sold at exercise. Consistent with existing research, exercises overall do not yield subsequent abnormal returns. However, we find a marked and significant difference in subsequent performance between exercises categorised as ‘high’ and ‘low’ sale proportion respectively. Therefore, while the exercise decision may appear uninformed, this study demonstrates that executives do use private information in their exercise and corresponding sale decisions. Further, near-the-money exercises produce negative abnormal returns, consistent with such exercises being relatively expensive. These results need to be reflected in the valuation of executive stock options, and hence the compensation executives derive from them

Executive Stock Option Exercises and the Predictive Ability of Transaction Value

This paper investigates the predictive ability of executives’ stock option exercises by categorising all exercises by the overall value of the transaction. This measure incorporates the cost to the executive of exercising the option, together with the income generated by the associated sale of stock at the time of exercise. As a result, we show that, in contrast to the existing literature, executive stock option exercises do have predictive ability for future stock returns. This is, however, limited to transactions that generate net revenue for the executive, a finding that is the reverse of the evidence relating to standard executive transactions