By this approach, the immediate impact of the 9/11 attack was to reduce real GDP growth in 2001 by 0.5%, and to increase the unemployment rate by 0.11% (reduce employment by 598,000 jobs.) Major economic effects were caused from the September 11 attacks, many people became scared and not trusting of the stock market causing global stock markets to drop sharply. The attacks themselves caused approximately $40 billion in insurance losses, making it one of the largest insured events ever. Event Summary. The United States' response to the 9-11 attack, namely the invasion of Afghanistan, had a deeply destabilizing impact on the Middle East and North Africa (MENA) region. In addition to ushering in war and instability, U.S. post-war policies sparked a strong wave of anti-Americanism across MENA.