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U.S. crude prices extended gains and Brent briefly turned higher on Thursday as the first hurricane of the 2015 Atlantic season sparked concern as the front-month September contract approached expiration.
Danny reached hurricane strength on Thursday, though it was relatively small and projected to weaken back into a tropical storm before reaching Puerto Rico on Tuesday, according to the U.S. National Hurricane Center.
"Even though it may not threaten any oil infrastructure, it is the first hurricane of the season," said Phil Flynn, analyst at Price Futures Group.
U.S. futures earlier retested support near $40 a barrel, falling to their lowest since the global financial crisis in 2009, and Brent fell to a fresh October contract low above $46 as a global supply glut and concerns about sputtering growth in China continue to weigh on oil prices.
Anxiety about global economic growth sent shares in Asia to a two-year low, German stocks extended losses and face their worst month since 2012 and British stocks hit their lowest since January.
"Global equities are a negative price driver for the oil and broader commodity complex," Dominick Chirichella, senior partner at Energy Management in New York said in a note.