Lack of meaningful good news + concerns about the upcoming October 18th earnings release.
News like Nokia's announcement of Life+ is not getting anybody thinking, "Oh boy, we've got 'em now!!" The only thing that's going to move Nokia higher is a successful WP8 launch (November??), news of NSN being profitable, and favorable cash burn statistics.
This quarter is going to stink for WP7 sales. The unfortunate timing of the announcement about WP8 effectively killed WP7 sales, and the fact that no WP8 sales will happen during this current quarter means sales numbers will be grim at best. So few analysts have lowered their sales projections at this point which is leading investors to believe that current estimates are still unrealistically high. The potential for a bad earnings miss is still very great.