What is the ruling on investing an amount of money in the Optic online stock trading company, which claims to be Islamic and free from commissions and usurious interest, and that it earns a percentage complementary to the client's profit percentage, rather than from their loss?

What has been mentioned is not sufficient to rule on the company. However, there are Sharia-compliant guidelines that, if met, make dealing with it permissible. These are: that buying and selling be limited to the amount of capital, that the conditions for selling gold, silver, and currencies be observed, that the investment systems be in permissible assets, and that overnight interest (Tabyit) and similar usurious practices be avoided. If these conditions are met, then dealing with the company is permissible. It is well-known that the stock market violates most of these conditions, and merely claiming adherence to Sharia guidelines is not sufficient.