At some point in 2013, I read (can’t remember where) that 2012 was a rare year for the S&P 500 where no day’s closing price was lower than the closing price for the first day. So if you bought on the first day of 2012, you never had a loss for the entire year. Well, the same thing happened 2013, so I just had to do some analysis. Below is a dimple.js chart built using rCharts with the minimum close price for the year divided by the close price for the first day of that year.
data source: Yahoo! Finance, Standard & Poors