1: It ruined the German Economy and caused more unemployment
Explanation: The German Economy by the time of the Great Depression was already pretty bad with the war and the consequences of the Versailles Treaty resulting in early political extremism but the Nazis still remained a fringe group until the stock market crash. The Stock Market Crash destroyed the barely recovering German Economy driving many more to political extremes such as Communism or Naziism
2: American investors pulled out of Germany
American Investors were investing into Germany heavily but with the stock market crash they withdrew their assets while Germany remained heavily in debt to them which ruined the financial system even more.