Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

How to split stock earnings?
If he asked you to invest his money with certain objectives which resulted in you buying specific stocks for him with his money, then sell all the stocks which you bought with his money and the capital and profits to him. You may want to calculate the trading fees that you incurred while buying these specific stocks and taxes from the sale of these stocks, withholding them to over the trading fees that you have already paid and the taxes that you might still need to pay. If you traded with his money no different than yours, then I would think of your investment account as a black box. Calculate the initial money that you both invested at the time you added his capital to the account, calculate how much it all is currently worth, then liquidate and return a percentage equal to that of his initial investment. You can account for trading fees and taxes, subtracting by the same percentage.