Maschinenbau Kiel GmbH designed, manufactured and marketed marine diesel engines, diesel locomotives and tracked vehicles under the MaK brand name. The three primary operating divisions of Maschinenbau Kiel GmbH were sold to different companies in the 1990s.

Rheinmetall acquired the military vehicles division in 1990. Siemens acquired the locomotive manufacturing division in 1992. Siemens sold the locomotive division to the current owner, Vossloh, in 1998. Caterpillar Inc. acquired the marine diesel engine division in 1997.

Both Vossloh and the marine diesels division of Caterpillar are still based in Kiel, Caterpillar continues to use MaK brand name on their products. The companies are major employers in Kiel.