iShares FTSE/Xinhua China 25 Index

Chinese stocks plummeted again yesterday.

The Shanghai Composite tanked 8.48% to 3725.56, while the Shenzhen Composite fell 7% to 2160.09. And the ChiNext, China's smaller equivalent of the Nasdaq, fell 7.4% to 2683.45.

U.S. and international investors need to understand what's going on in China and position themselves to profit on a full-blown market crash there that could ignite global contagion...