Nikkei tumbles again but U.S. futures look bright.

 Japanese stocks suffered their fourth sharp decline in eight sessions as the Nikkei fell 3.7%, taking its losses since the market turmoil began on May 23 to 17%. "The (Japanese) market has yet to bottom, and volatility will likely remain for another month," says asset manager Yoshihiro Okumura. Much of Europe reversed earlier losses to turn green - possibly due to the PMI data? - while U.S. stock futures were up premarket following the late sell-off on Friday.