If this does turn out to be the reason behind this, I just know what's going to happen next. The idiots in the media, and the government (but I repeat myself) will use this opportunity to smear Wall Street further and they will call for even more regulations and use this to push that horrible bill through Congress.
Now that I think about it, aren't there protections in place that can detect this sort of thing and prevent it from happening? I can understand if someone misplaced a decimal point and traded 1,000 of something instead of 100, but this sounds far too big to not be noticed by someone.