[1] His siblings were art historian and cultural theorist Abraham “Aby” Warburg; chief architect of the Federal Reserve Board of the United States Paul Warburg; Felix, son-in-law to Jacob Schiff and partner at Kuhn, Loeb & Co.; Fritz; Olga; and Louisa.

As head of that firm, he advised Kaiser Wilhelm II prior to World War I.

From 1933, he served on the board of the German Reichsbank under governor Hjalmar Schacht.

He sold the bank because the 1935 Nuremberg laws set the framework and campaign of Aryanization.

His company did deals on Wall Street with help of people like Alan Dulles, and he maintained a close relationship with John J. McCloy over the years.