Shenzhen margin financier’s 5-for-1 funding goes some way to explain why a sense of deja vu is filling China’s stock market rally

• Margin financing by private lending firms fuels leveraged trading as A share index rallied to its biggest one-day percentage jump in three years
• China’s regulator cracks down on regulated margin financing after 2015 stock rout, but private lending is hard to trace, analysts say