台灣在近年來因為外在環境改變、企業本身需要以及自政府陸續通過包括相關購併法令等種種內外在因素之配合下，掀起一股合併風潮，而換股比率之多寡也成為各方關注之重點，所謂換股比率乃指存續公司為換取目標公司之一股股票所給予之存續公司股數。其中換股比率之關鍵在於換股比率之高低不但關係著參與合併者對於存續公司之利益分配，同時也牽涉到股東財富水準之增減。因為對於目標公司之股東而言，換股比率愈高，其所換得之存續公司股票總值也愈高；但是對主併公司股東而言，較高之換股比率不但使合併後公司流通在外股數增加，也會使目標公司之股東可透過擁有存續公司較高之持股比率，進而擁有存續公司較高之控制權。而當換股比率過低，無法引起目標公司股東之興趣時，則此合併案件將會告吹。因此凡是涉及普通股交換之合併案件，「換股比率」必為一重要且影響合併成功與否之關鍵議題，因此本文以1994年1月1日至2004年12月31日之台灣公開發行公司之合併案件為資料分別對Larson and Gonedes (1969)利用合併後之預期本益比以及Yagli (1987) 利用合併後之預期成長率所發展出之換股比率決定模型進行實證研究。
實證結果顯示，LG模型相較於Yagli模型擁有著更好之捕捉能力，LG模型捕捉到20％以上之合併案件，而Yagli模型僅僅捕捉到4%之合併案件。同時，兩種模型之實證結果皆顯示出在合併案件中，目標公司股東之財富水準於合併後增加之機會將高於主併公司之股東。但不論是LG模型或是Yagli模型皆有著許多限制，導致其實證結果並不如預期，如兩者於衡量股東財富時接受到單一期間所限制，若遭遇合併綜效需耗費一段時間才能發酵之案件，將無法有效捕捉，例如合併之目的為節稅、合併之目的為專利權等等。

In stock-exchanged mergers, the determination of an exchange ratio is an important issue. The exchange ratio represents the number of shares that the acquiring firm offers in exchange for one share of the target firm. The ratio is critical since it does not only determine how the possible synergy gains are shared between the firms involved, but it also determines whether the wealth positions of the parties will experience improvement or diminution as a result of the proposed merger. The purpose of this paper is to verify the validity of the LG model which is based on the expected post-merger price-earning and the Yagli model which is based on the post-merger dividend growth, respectively. The models are tested on the sample of mergers which involved only stock offers for the period from 1994 to 2004.
The results show that the LG model has greater empirical validity than the Yagli model. There are 20% of the sample mergers are conforming to the stockholder wealth premise predicted in the LG model at least, but only 4% of the sample mergers are conforming to the stockholder wealth premise predicted in the Yagli model. In addition, this paper also finds that the chance to improve the wealth position of the stockholders of the target firm is relatively larger than the acquiring firm. The empirical results not as good as the expectations are due to the limitations of the models. For example, the one period wealth constraint is too restrictive. It is believed that benefits of the merger may take a period longer than a year; hence, the PE ratio and the growth rate after a year may be greater. If this is the case, the first year stockholder loss could be more than offset.

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