Invessting.com - Oil futures gave up early gains to trade near three-month lows on Friday on a persistent supply glut that has cut prices by up to 13 percent since the start of November. U.S. crude West Texas Intermediate dipped 11 cents to $40.43 a barrel as of 0731 GMT, after edging up in earlier trades. Crude futures have already lost around 60 percent of their value since mid-2014 as supply exceeds demand by roughly 0.7 million to 2.5 million barrels per day to create a glut that analysts say will last well into 2016.