West Texas Intermediate futures for February delivery is currently at $36.66 (+0.16%), while Brent crude is at $36.64 (+0.49%) after suffering loss of more than 3% in the previous session. The Energy Information Administration reported an unexpected rise of 2.6 million barrels in U.S. crude oil inventories in the week ending December 25. WTI and Brent lost 31% and 36% of their value in 2015 respectively.

The supply glut will worry investors in 2016 too as OPEC's leader Saudi Arabia rejects calls for output target revisions and maintains high production levels in an attempt to defend its market share.