Since the 1980s a significant increase of equity carve-outs (ECOs), i. e. the going-public of a subsidiary of an exchange-listed parent firm, could be observed. Equity carve-outs have been subject to discussion in the context of divestitures and as a method of corporate restructuring of conglomerate firms. Equity carve-out transactions are exceptional as they combine a corporate restructuring and a simultaneous financing through an initial public offering. The studies on the announcement returns of equity carve-outs focus on the restructuring aspect of the ECO transaction, i. e. the separation of a subsidiary from its conglomerate parent and the subsequent disposal. This empirical study, however, focuses on the corporate finance aspect, i. e. the capital raising in the equity carve-out transaction through an initial public offering. Some of the largest initial public offerings in Germany including the IPOs of Infineon Technologies AG (Siemens AG) and Deutsche Postbank AG (Deutsche Post AG) have been structured as equity carve-outs. Key aspects of the research interest on initial public offerings include significant positive initial returns manifested in the underpricing phenomenon and the negative long-term performance of IPO stocks. The occurrence of positive initial returns and the subsequent negative long-term performance for initial public offerings of subsidiary firms results in an "ECO Puzzle", which will be examined for the largest sample of equity carve-outs in Germany to date.