This diploma thesis deals with the unnoticed stake building of a target company before its takeover.After a introduction related to the recent situation of the M&A market, the concept and the intention of disclosure obligations are defined and described. The role of EC law as a general basement is shortly introduced, before national rules and regulations concerning disclosure obligations [Stock Exchange Act (Börsegesetz), Law on Takeovers (Übernahmegesetz) and the Austrian Corporate Governance Code (Österreichischer Corporate Governance Kodex)] are presented and compared.The second part of the paper defines the meaning of stake building in the run-up to a takeover. A comparison of the interests of the involved parties should demonstrate the different intentions which are conflicting throughout a takeover procedure. With an economic and legal analysis of two selected financial instruments (options and cash settled equity swaps) the `stealth approach? to a target company before initiating the official takeover process should be outlined. In the center of consideration stands the question, if those financial instruments are covered by disclosure rules according to the current Austrian legal situation.Finally, the presentation of the takeover process of the German Continental AG by Schaeffler should illustrate the by-passing potential of financial derivatives under German law. Throughout this spectacular takeover, cash settled equity swaps were used to avoid disclosure obligations resulting from German droit. After this presentation of Schaeffler?s takeover strategy, the ruling of the German Federal Financial Supervisory Authority (BaFin) and the reactions of the German-speaking teaching are analysed, before the major conclusion are summarized.