Futures in New York, little changed on Friday, are down 2.9% this week. Developing-nation equities slipped into a bear market, increasing concerns that the tumult could sap energy demand. Meanwhile, US government data on Thursday showed crude inventories at Cushing in Oklahoma rose for a fourth week, with total stockpiles of gasoline and distillates also expanding.

The anxiety over emerging economies is the latest global event to damp market sentiment. The escalating trade tension between the US and China has also led investors to shun risk, with crude prices slumping since July. Still, speculation that US sanctions on Iran could tighten oil markets despite OPEC’s pledge to boost output has countered the bearish sentiments.

“The worries about demand and a possible spillover from emerging markets are weighing on prices,” said Hans van Cleef, senior energy economist at ABN Amro Bank NV. “We have tested breaking higher, but that failed, so now we have a temporary setback. I still expect the market to turn higher at some point, probably driven by Iran.”

West Texas Intermediate for October delivery traded at $67.81 a barrel on the New York Mercantile Exchange, up 4 cents, at 11.04am in London. It’s set for the biggest weekly drop since July 13. Total volume traded was about 28% below the 100-day average.

Brent for November settlement lost 1 cent to US$76.49 a barrel on the ICE Futures Europe exchange. It’s on course for a 1.2% slide this week. The global benchmark crude traded at a US$8.91 premium to WTI for the same month.