RE: House Positions...It's a single trader, Fix. The trading by the other houses is done by multiple unrelated investors in each of those houses you mentioned and therefore reactions are not consistent. Anonymous and 2 of the other houses are the most frequent beneficiaries of FIMAT's actions.
Why watch the beneficiaries? Why not just step in front of them when FIMAT looks like he's about to swing it? There are situations where FIMAT is pretty consistent. When he does something different it's because he's usually doing something different.