EDIT: Here is a graph highlighting how important including dividends is: https://i.imgur.com/YZSq6K3.png
Another consideration is taxes. The short-term gains produced by selling after 6 months are taxed at normal income rates (or slightly higher), as is the interest from the "risk free" interest-paying investment held the other 6 months. Long-term capital gains and dividends are taxed at favorable rates.