In the past, traders were siloed and no individual trader would have access to the total positions of all the traders on the floor. Some firms still operate this way, though it's more common for trading operations to be broken up into "pods" or teams of traders and analysts.
The industry has largely moved away from this structure for a variety of reasons. One of the problems is that traders start to try and undermine each other, since the only thing that matters is your personal pnl. Another problem is that traders can unknowingly all pile into the same investments, resulting in massive risk. This is part of the reason why the Great Recession was so bad.
The industry has largely moved away from this structure for a variety of reasons. One of the problems is that traders start to try and undermine each other, since the only thing that matters is your personal pnl. Another problem is that traders can unknowingly all pile into the same investments, resulting in massive risk. This is part of the reason why the Great Recession was so bad.