What are the risks with stocks?

Stocks carry a much greater risk of short-term losses than bonds or cash (the other two major asset classes). Since World War II, Wall Street has endured six bear markets (defined as a sustained decline of more than 20% in the value of the S&P 500). As a result, it's generally not a good idea to invest a big chunk of money in stocks if you'll need to spend the money within five years or so.