Adolf Hitler's financiers, the Thyssen family, formed UBC to manage investments in America. The US congressional report described Union Bank as an "interlocking trust" with the German Steel Trust. UBC was also involved in raising funds for Germany and illegally transferring aviation fuel technology to the Luftwaffe.
A July 1942 New York Tribune front page article about the bank was headlined "Hitler's Angel has 3 million in US bank"; ("Hitler's Angel" being Fritz Thyssen). This prompted the congressional investigation which closed UBC.