Reggie Middleton of BoomBustBlog.com breaks down Goldman Sachs' proprietary trading business model. His analysis could also be applied to the high-frequency trading firm Virtu, which is going public today on the narrative that it suffered only one day of trading losses IN FIVE YEARS. Never gamble against a guy who has a city for a nickname, and stay out of the dark pools where pirhana like Goldman & Virtu linger.