Major exchange-traded funds pegged to moves in crude oil are on track for their biggest weekly gain in more than a year, boosted as OPEC unexpectedly reached a deal to cut production - a move that could address the commodity's oversupply and help stabilize prices. Crude oil /zigman2/quotes/209723641/delayed CLF27 0.00% has surged 11% this week, as have the United States Oil Fund LP /zigman2/quotes/203483736/composite USO +0.28% and the iPath S&P GSCI Crude Oil Total Return Index exchange-traded note /zigman2/quotes/204600377/composite OIL -0.08% . Among other funds, the United States 12 Month Oil Fund LP /zigman2/quotes/209867783/composite USL +0.22% is up 8.6% for the week while the PowerShares DB Oil Fund /zigman2/quotes/202740135/composite DBO +0.17% has climbed 10.2%. The VelocityShares 3x Long Crude ETN a triple leveraged fund that offers 300% of the daily move of its underlying index, has skyrocketed about 32% thus far this week. In all the cases, they are on track for their best weekly performance since August 2015. On Wednesday, the Organization of the Petroleum Exporting Countries and other major oil producers reached a deal to curb daily oil production by 1.2 million barrels a day, bringing it to a ceiling of 32.5 million barrels.