Ginger Zengge had a good feeling about the stock market. Though the Shanghai Composite Index had risen 150 per cent over the previous 12 months and just hit a seven-year high, she saw a “buy” signal that other investors had probably overlooked: President Xi Jinping’s birthday.

“When the index dropped on June 15, which happened to be Xi’s birthday, I thought, ‘Yes, now is the time to buy!’,” said Ms Zengge, 26, who works for a security ratings company in Beijing. She bought more shares later that month.

Unfortunately for Ms Zengge, she decided to buy near the very top of a remarkable bull run in China stocks. After reaching a peak of 5,166.35 on June 12, the Shanghai index fell 30 per cent in just three weeks. By July 3 the Shanghai and Shenzhen exchanges had shed almost Rmb18.6tn ($3tn) in market capitalisation.