Leverage has played a big part in the rally: margin financing for share purchases has increased five-fold over the past year to more than 2 trillion yuan.
One of the scariest sentences I think I've read this year.
See also:
Of seventeen hundred stocks on the Shenzhen Exchange, only four have fallen this year, and more than a hundred have seen their shares rise more than five hundred per cent. The Shenzhen Index as a whole has doubled since January, and is up more than two hundred per cent in the past year.
from the New Yorker.