Only a small percentage of the IT people worked on those. Mostly we built and maintained systems to track and report on trades, keep track of credit, figure out profit/loss on books, make sure traders didn't bet the company on risky trades, scrape numbers off of websites and put them in a db. We also pulled a lot of numbers into spreadsheets so analysts could make charts to email out to the traders.

It was much as the GP says... long desks, lots of noise and distractions, poor technology base (they upgraded to WinXP with IE6 in 2009). On the plus side, the pay was good (high 5, low 6 figures), multiple monitors, lots of snacks and drinks in the kitchen, catered lunch, good healthcare...