Investing is not inherently unethical. If you're directly buying a tobacco company's bonds, then yeah, you're helping evil to prosper, but consider the following scenarios. (Remember that money is just a number - what it represents is that you've done work for other people, and in exchange other people are willing to do a certain amount of work for you. Compared to barter, money provides a magical layer of indirection as it sloshes around the economy - you may make widgets for FooCorp, and the money you earn allows you to buy gizmos from BarInc, even if nobody from BarInc has ever heard of a widget.) * You have money, but right now you're not interested in buying anything with it. Person X doesn't have money, but would like to have a car right now instead of waiting for a year to accumulate enough cash, or would like to live in a house right now instead of waiting for 30 years to accumulate enough cash while living in a tiny apartment. If you loan Person X money, they get to buy that car or house right now (yay for them!). In exchange for not being able to access your money for a period of time, and for taking on the risk that you might not be paid back, Person X agrees to pay you back extra money. (The original pile of cash that changes hands is called the "principal", while the extra pile of cash is called the "interest".) This is super awesome for you - you've earned extra money by doing financial work, instead of the usual physical work or mental work at your day job. * There are many other reasons why someone might want to borrow money (i.e. giving you an opportunity to lend to them). A company might want to expand its operations, but needs a temporary infusion of cash to do so. Once expanded, they predict that they'll make more money than before, so after paying you back their position will have improved. Or perhaps a country needs to buy a bunch of tanks in order to fight Nazis, or zombies, or zombie Nazis. There are ways to do this wrong (see the epic h

The only way you're likely to be making profits at the expense of others is if you pick stocks in industries with significant externalized costs... which I admit may be hard to avoid, especially with an index fund, depending on the true impact of CO2 emissions and on the status of corresponding Pigovian taxes that apply to your investment targets. Otherwise, for the most part you're making profits at the profit of others. Life isn't a zero sum game. Capital markets want your dollars because investment can help create and improve products that are worth more than their inputs plus the investment, and "worth more" is in the opinion of the people who buy those products, who after all wouldn't have bought them if they didn't value them more than the money they spent. Likewise for employees as well as consumers - even "sweat shops" with dismal conditions by first world standards have to supply locally-high wages to attract workers, and historically this ends up raising wages for the country as a whole. Your profits are (infinitesimally) reducing the profits made by other investors. Microeconomics says that if you increase the supply of something, including capital, the price paid to the suppliers typically goes down. But no wealth goes away in this scenario. Other investors' loss is exceeded by employees', consumers' and your gain, and since consumers and employees are on average less wealthy than investors the net gain is even greater in utility than in dollars.