The leaderboard is a motivational/team building tool and also a way of keeping customers 'sticky'.
There are 2 types of leaderboard.
Monthly/Weekly - these leaderboards rank traders by consistency and good trading behavior.
Daily - the daily leaderboard ranks by P&L but will downrank someone that does something silly like scale into a massive offside trade. The rating is different on the daily leaderboard because you can't really rate consistency over just one day.
There is a public leaderboard, which traders can opt in/out of. Firms can also have their own internal leaderboards. Brokerages can do the same thing.
In the above screen shot, we can see the three winners and below that a list of all the participants.
To select a specific group, use the group selection and refresh button: 
To change the dates shown - use the calendar: 
Users can elect to have their individual trades displayed. If you see the 
or 
you can click to see the individual positions.
