As Commissioner of Currency (1923) he applied a rigorous monetary policy to stabilize the mark after its collapse in that year. He took part in reparations negotiations but rejected the Young Plan (1929). Under Hitler he became Minister of Economics (1934–37), responsible for Nazi programmes on unemployment and rearmament. Rivalry with Goering caused his resignation. In 1944 he was imprisoned in a concentration camp for his alleged involvement in the July Plot to assassinate Hitler. At the Nuremberg Trials (1946) he was acquitted.