China's Shanghai Composite fell approximately 43% from its June 2015 peak to its August 2015 low during the 2015 stock-market turbulence.
The index reached 5,178.19 on June 12, 2015. It then dropped rapidly as leveraged investors faced forced selling, confidence weakened, and concerns grew about the sustainability of the earlier rally. By August 26, the index had fallen to 2,927.29.
Chinese authorities responded with measures including trading restrictions, support for share purchases, and interventions involving state-linked institutions. The turmoil also affected global markets, particularly during the worldwide sell-off in August.
The 43% figure describes the fall between the Shanghai Composite's identified peak and low in that episode. It is different from the much smaller single-day percentage moves often reported for individual sessions.