Shares of stocks listed on the Shanghai Stock Exchange closed to their lowest in nearly 41 months, with class B shares of small- and medium-cap companies getting clobbered most due to new rules for troubled firms.

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Buying Chinese stocks listed in Hong Kong, especially Chinese bank stocks (H shares), has been popular with foreign investors.

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Right now, BATS handles just under 4% of trading in NYSE-listed stocks, or about 74 million shares a day.

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The window is nearly shut for Chinese companies to go public in the U.S. while shares of listed Chinese stocks on NASDAQ and the NYSE are bottoming out.

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