The competitors for the DB Class 121 included two of the forerunners of Bombardier Transportation: German locomotive manufacturer AEG Schienenfahrzeuge, a part of AEG which was controlled by Daimler-Benz at the time; and ABB Henschel, a German locomotive manufacturing branch of Swedish-Swiss company ABB. Components of both the AEG and ABB concepts were built into the prototypes of the DB Class 120 for trials from late 1991. AEG followed up its development effort by building an experimental universal locomotive, the 12X. This locomotive can be considered the predecessor of the TRAXX family. The 12X was delivered in June 1994 and, although owned by AEG, was designated Class 128 by DB. The 12X featured several innovations compared to the Class 120, including water-cooled inverters based on GTO thyristors, a new final drive concept with pivot axle bearings on both sides, and a new bogie concept with a short wheelbase of . The locomotive also had a modular design, allowing the derivation of different versions for different operational needs, and thus it formed AEG's basis to compete for the new orders of Deutsche Bahn's business areas. Meanwhile, ABB developed its own design of a modular electric locomotive platform, the Eco2000 concept. ABB's concept included a version of its Flexifloat high-speed bogie family with a wheelbase of ; and biodegradable ester cooled inverters with GTO thyristors and an also ester cooled main transformer, which can be considered the origin of the inverters and transformer of the first generation of TRAXX locomotives.