The amendment of the German Energy legislation in April 1998 breaks up the regulated monopoly and transforms the monopolistic electric utility industry into a competitive electric power industry (cf. Erdmann 2000). The new energy legislation introduces competition in the generation and trading business, whereas the free choice of supplier on the wholesale and retail level creates additional competitive pressure on the trade chain (cf. Haupt and Pfaffenberger 2000). As a consequence of the liberalization process, transaction relations, trading processes, contract designs, and market structures are undergoing radical changes (cf. Bower et al. 2000).