Profit from buying and selling stocks comes from the exchange value of the trade, and not the surplus value that's extracted from workers. As @GrandAyatollaLenin already pointed out, only dividends would come from company profits, but as a small investor it's very unlikely you'd make any money from dividends anyway.
Aside from this, I'm not sure there's a solid case that participation in the current unethical system is always itself unethical, and it's very similar to the "you call yourself a socialist, yet you use an iphone" argument. You most likely already give money to unethical companies by purchasing their products, and you almost certainly give money to unethical governments through paying taxes. It's all unethical at a high level, but is it unethical for you as an individual to participate if your actions do not directly prop up the system and/or cause harm to people? If you're a small business tyrant, I'd assume it's unethical to mistreat employees and pay them garbage wages, but would it be unethical if a business you own treats employees significantly better than similar businesses, or in some way serves to help a disadvantaged community (tribal businesses, as an example)? At a much higher level, is it unethical for countries with socialist goals (like China) to use capitalism as a stepping stone towards achieving those goals?
I realize I might be opening a can of worms on the 2nd point, but I think it's worth discussing what level of participation in the existing system should be deemed unethical. Rarely is it ever a black and white issue.
EDIT: Just to be clear, my argument on point 2 isn't to say that any form of private ownership isn't problematic, because it is, but to question whether every particular instance of that (or participation in general) should be automatically lumped into the same ethical category, regardless of the real world impact on individuals and communities.
A couple of thoughts I have on this:
Profit from buying and selling stocks comes from the exchange value of the trade, and not the surplus value that's extracted from workers. As @GrandAyatollaLenin already pointed out, only dividends would come from company profits, but as a small investor it's very unlikely you'd make any money from dividends anyway.
Aside from this, I'm not sure there's a solid case that participation in the current unethical system is always itself unethical, and it's very similar to the "you call yourself a socialist, yet you use an iphone" argument. You most likely already give money to unethical companies by purchasing their products, and you almost certainly give money to unethical governments through paying taxes. It's all unethical at a high level, but is it unethical for you as an individual to participate if your actions do not directly prop up the system and/or cause harm to people? If you're a small business tyrant, I'd assume it's unethical to mistreat employees and pay them garbage wages, but would it be unethical if a business you own treats employees significantly better than similar businesses, or in some way serves to help a disadvantaged community (tribal businesses, as an example)? At a much higher level, is it unethical for countries with socialist goals (like China) to use capitalism as a stepping stone towards achieving those goals?
I realize I might be opening a can of worms on the 2nd point, but I think it's worth discussing what level of participation in the existing system should be deemed unethical. Rarely is it ever a black and white issue.
EDIT: Just to be clear, my argument on point 2 isn't to say that any form of private ownership isn't problematic, because it is, but to question whether every particular instance of that (or participation in general) should be automatically lumped into the same ethical category, regardless of the real world impact on individuals and communities.