Yes, you can. It is a reality of the market that no reward comes without risk. You can lose money buying a bad investment, but you can also lose by buying a good investment at the wrong time. When it comes to the financial markets, there are endless possibilities for making and losing money. Unless all the funds in your brokerage account are sitting in uninvested cash, there is a risk you will lose money. Another way of looking at that, however, is that a brokerage account sitting full of uninvested cash isn't at risk of making any money either. You can use strategies like asset allocation and diversification to reduce the risk of you losing money, but you will never fully eliminate it without also eliminating your chances of making a decent return.