This is How Much Money You Should Have in Stocks — at Every Age By Ian Salisbury If you want a secure retirement, you can’t just save. You also need to make sure your investment portfolio keeps pace with inflation. For most Americans, that’s going to mean investing in the stock market, whether inside a 401(k) or at an online brokerage. But determining how much of your money to put in stocks can be tricky. When you’re young, the hardest part may simply be getting started.