Nothing is zero risk, including owning a car; include the risk in your calculation. Your time frame is not one year, but typically 3-5. If your loan is at 2%, you don't need your stocks to hit 8% every year. You need them to be no worse than 2% p.a. over the entire period of your loan. That's significantly smaller risk than the risk of stocks not performing at your expectation of much higher return.