When I'm bored I sometimes check the trading to see which houses are involved in the buying and selling.....I don't attach much meaning to it....I've found out that there are more firms than I can name, when I find one I've never heard of before I look at their web page...Altainvestors (or something starting with Alta) was one, Paradis seems to have dealt with them before when he was at Penn West, haven't seen them for a while though.....

ITG just popped up, and its nothing HUGE or even close....but for RVX its decent size.

So I looked into them for fun:  http://www.itg.com/solutions/execution/algos/

Some interesting stuff about alogrithims there....which is something I'm slowly learning about.