• The Korean Journal of Financial Management
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• v.22 no.1
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• pp.37-69
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• 2005

This study intends to verify whether stock repurchase, as well as stock dispositions, affects shareholder's wealth and also whether repurchase/dispositions has varying impact de-pending on its purpose. According to empirical analysis, announcement of stock repurchase results in positive abnormal returns when the objective of stock repurchase is stock price stabilization or cancellation of shares. However, when the purpose of stock repurchase is granting incentives to executives/employees, we get the negative abnormal returns. Also, the termination of stock trust for reason of expiration or stock dispositions of which goal is to give incentives to executive/employees has a negative impact on stock price, whereas direct dispositions of stock to raise cash or to improve financial structrue are shown to significantly increase the wealth of shareholders. Cross-section analysis also confirms that stock repurchase and dispositions has different impact on excess returns depending on its purpose. The results of this study imply that the dispositions of stock should be regarded as an important financial strategic tool to be used by companies and what's more, such studies dealing with stock repurchase or dispositions should take firm's purpose into consideration in their approach.

• Journal of KIISE:Databases
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• v.34 no.3
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• pp.179-192
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• 2007

This paper addresses an approach that recommends investment types for stock investors by discovering useful rules from past changing patterns of stock prices in databases. First, we define a new rule model for recommending stock investment types. For a frequent pattern of stock prices, if its subsequent stock prices are matched to a condition of an investor, the model recommends a corresponding investment type for this stock. The frequent pattern is regarded as a rule head, and the subsequent part a rule body. We observed that the conditions on rule bodies are quite different depending on dispositions of investors while rule heads are independent of characteristics of investors in most cases. With this observation, we propose a new method that discovers and stores only the rule heads rather than the whole rules in a rule discovery process. This allows investors to define various conditions on rule bodies flexibly, and also improves the performance of a rule discovery process by reducing the number of rules. For efficient discovery and matching of rules, we propose methods for discovering frequent patterns, constructing a frequent pattern base, and indexing them. We also suggest a method that finds the rules matched to a query issued by an investor from a frequent pattern base, and a method that recommends an investment type using the rules. Finally, we verify the superiority of our approach via various experiments using real-life stock data.