I noticed shortly after HSX introduced the player profile page that it was updated in real time while the trader watchlist and leaderboards were updated daily (at reset).
I invented the process of taking the net worth on the trader watchlist and comparing it to the player profile to see the daily gain for players.
I was talking to another HSX player in chat and told them how I was having a great day at HSX and they made a comment that they were likely not doing too good. I looked them up and told them how they were doing and they were suprised (because they had just logged into their account and saw the amount I told them).
That player asked me how I did it and I explained the process to them.
About a month after that somebody was on the boards bragging about how much money that they were making that day, and I corrected them using my process (because they were lying). Another player asked me how I could see how much players had made during the day... and my friend chimed in and leaked how to do it.
Nosy was created a few months later.
Nosy simply does the same thing (compares a player's profile to their LTD Leaderboard ranking to get a daily gain.)
My calculator is lonely these days... but I get more done.