U.S. stock index futures were mixed to higher ahead of Friday's open, as investors get ready for the start of a new trading year. Trading has been lighter than usual this week as investors get ready for the new year. Consequently, key trends and potential market-moving events will be of key importance to market-watchers from now on, as the final day of trading looms.

Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., on Monday, Dec. 18, 2017. Michael Nagle | Bloomberg | Getty Images

In the penultimate session of the year Thursday, U.S. stocks finished slightly higher, with the Dow Jones industrial average securing another record close. Meantime in markets overseas, Asia posted mild gains on Friday while European markets fluctuated in early trade. Switching focus back to the States, with little data or earnings on the trading day's horizon, investors are likely to be paying close attention to the moves in markets such as commodities and bitcoin, as each market continues to show wild swings. Looking to energy, oil prices rose on Friday, with U.S. crude trading above $60, hitting highs seen last in mid-2015, as a decline in U.S. production and commercial crude inventories lifted sentiment.