What rules should be set for a "fantasy stock picking" contest?

External question — Personal Finance Stack Exchange Author: its just for fun Original post: https://money.stackexchange.com/questions/118365 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I'm pretty into stock trading, as are several of my friends, and we love to joke around about trading and debate strategies. It's a hobby for us just like watching sports or a TV show, and we all have long-term portfolios doing pretty well. We've talked about doing a contest where we all pick stocks and see who can do better in a given month. What rules would you recommend making to keep it fun? Here's what I'm thinking: We each open accounts with some other broker than our main portfolio, with a set amount like $500. No one knows each other's stocks but we report each week what our balance is. We either can trade as much as we want or just rebalance once a week, but no more money can be put in after it starts. After 30 days, whoever did the best gets everyone else's gains, minus 22% to cover short-term cap gains tax. So everyone gets their original buy-in back, but the winner gets $100-150. We've done fantasy basketball and football pools with $20-50 buy-ins so the idea of "owing a friend money" won't be an issue. I'm also not interested in hearing how picking short-term gains isn't indicative of "being a good trader". I know that, this is just for fun. Has anyone done this and has any other rules you'd recommend to keep it fun?