HSI may "lead" the US market sometimes because of its large foreign capital presence. Sometimes I see significant futures and cash divergence in the afternoon and more often than not it has some follow thru in the US market usually because of some surprised figures. It makes sense because some large firms might get the data ahead and the liquidity is better in HSI at the time than in the US overnight market. I don't know if we could make money off this observation though. Never tried it and the leading relationship could be just in my head.