The energy sector has been the best performing S&P 500 sector so far in 2016, rising 24.3%, but investors should proceed with caution in 2017. Keith Bliss, senior vice president with Cuttone & Co., said the 2016 growth comes amid a stabilization in oil prices after the sector was slammed in 2015. According to Bliss, oil companies must get used to $50 to $60 oil. Plus, should OPEC fail to adhere to its proposed production cuts, which take effect in January, that may ding energy stocks, which are banking on higher oil prices, according to Bliss.