Some online brokerage firms have required minimums, but the amount you need to get started has more to do with what you invest in than where you open an account. The minimum investment amount depends on your broker and the type of investment. Most mutual funds have minimum investments of around $1,000, though there are notable exceptions. Since a major advantage of investing in ETFs is that they trade like stocks, the minimum to start investing is typically the price of one share, but if your broker offers fractional shares, you may be able to invest even as little as $1.