does the analysis also includes HFT traders?
Also I remember hearing that Goldman Sachs didn't have a single day of trading loss. Maybe the smaller Quant funds are loosing out on talent to the bigger firms?
While its true that HFT groups tend to have great win/loss records (2), those "trading profits" basically have nothing to do with the banks' HFT groups. The banks basically all had very big carry trades on -- they were borrowing at short term rates from the fed and lending at higher rates to others and collecting the spread. Since the Fed was desperate to pump money into the system, they allow banks to borrow cheaply and essentially guaranteed the carry trade for the short term.
That sort of trade tends to be highly stable in static rate environments and you get very smooth return profiles. Since they knew the Fed was essentially backing the trade, they piled onto the trade and that particular component of the firms' total daily P&L just dwarfs the rest of their "real" prop trading operation P&L.
Of course, it won't last forever. Its the sort of trade that works until it doesn't -- Long Term Capital Management basically had super levered carry trades on which gave them a really high sharpe ratio until things got choppy and they blew out.
1: http://www.businessweek.com/news/2010-05-11/-perfect-quarter...
2: Tradeworx claims to have not had a down day in 4 years, reference http://dealbook.blogs.nytimes.com/2010/05/17/speedy-new-trad...
To clarify: the size of the fund is not necessarily an indicator of whether it will be successful or not.