Well-supplied markets and weakening demand for crude concern American drillers.

The U.S. crude oil price benchmark, West Texas Intermediate, fell 8% to less than $68 a barrel, the lowest level since last week. The global Brent crude price benchmark likewise fell about 8%. Major stock indexes ended the day in positive territory.

Tensions remain high, but a sustained rise in oil prices requires a fundamental reduction in global oil supply. That’s not our base case.