The Shanghai Composite reached a closing high of 5,178.19 before China’s 2015 stock-market crash.
The index reached that level on June 12, 2015, after a powerful rally had lifted mainland Chinese shares. The boom was supported by retail investor participation, margin borrowing, and expectations that economic reforms would improve market prospects.
After the June peak, share prices fell sharply. The decline accelerated in July and August, despite official efforts to support prices and stabilize confidence. On August 24, often called Black Monday in China, the Shanghai Composite fell 8.49% in one session.
The episode is sometimes confused with China’s separate market turmoil in 2015–16 as a whole. The 5,178.19 figure is specifically the June closing peak, not the market’s intraday high or its later recovery level.