Stocks in the U.K. darted between small gains and losses Wednesday, with commodity shares remaining under pressure, but the benchmark FTSE 100 was still on track to finish higher for the month.

The FTSE 100 UKX, -0.08% was up 1 point at 6,821.97. But the London benchmark is still poised for a 1.4% gain for the month of August.

“Cheaper oil and a stronger U.S. dollar continue weighing on the U.K.’s stock market,” Ipek Ozkardeskaya, senior market analyst at London Capital Group, in a note. “The high volatility is a sign of stress. Mining stocks and energy companies remain the most sensitive sectors”, she said, noting West Texas Intermediate oil prices CLV6, -0.54% are headed toward $45 (£34.24) a barrel.