Betty Liu, Executive Vice Chairman for NYSE Group, explains:

Do election years have an impact on the markets?

So, the short answer is it depends. There's lots of factors that affect the markets, right. But there are some trends. So, the S&P has had its best performance in the year before elections and the second-best performance on election year. Now since 1928, we've had 23 election years and the S&P has had negative returns only four times in that duration.