Albert starts hacking on a prototype project on june 2018. He works full-time on it. In march 2020, the project looks promising (made ~3000 usd) and he convinces Bob, a random guy he met on reddit, to join him. With the help of Bob, things take off. They invest 40k of their own savings in the project. From march to december 2020, average growth is about 100% per month. In July, Carl joins the project. In January 2021, growth slows down to about 30% per month, and total profit is 20M. In march 2021, Dan joins the project.
All of Albert, Bob, Carl and Dan work full time and plan to continue working for a long time on the project and consider themselves cofounders.
The project is a proprietary trading algorithm whose future profits are uncertain depending on competition and market conditions. Their plan is to scale up as a proprietary trading firm.
What would be a fair equity split between A, B, C, and D ?