"The list of things weighing on the market is long," said Olivier Jakob, managing director at Petromatrix GmbH in Zug, Switzerland, who correctly predicted that this year's oil rally would stall. "There's the Chinese PMI, the Greek referendum taking EU leaders by surprise, the euro-dollar collapsing."

Oil for December delivery declined as much as $2.06 to $91.13 a barrel in electronic trading on the New York Mercantile Exchange and was at $91.45 at 8:50 a.m. London time. Futures fell 0.1 percent yesterday and climbed 18 percent in October.

Brent oil for December settlement dropped 1.4 percent to $108 a barrel on the London-based ICE Futures Europe exchange. The European benchmark contract's premium to U.S. futures was at $16.55 a barrel, compared with a gap of $16.37 at yesterday's close, the lowest in more than four months.

Eoin Treacy's view High oil prices act as a tax on consumption. Oil's surge earlier this year was an economic headwind and Brent crude's persistence above $100 has been a cause for concern. This strength was at least partially supported by the loss of Libyan supply but as the political situation improves that should become less of a worry.

Generally speaking stock markets and oil have rallied concurrently over the last year while the US Dollar and Treasuries have been the instruments of choice during all too frequent periods of uncertainty. The US Dollar's October decline was at least as abrupt as the rally experienced by most stock markets over the same period. The Dollar Index surged from the 75 area on Monday and a sustained move below that level would be required to question current scope for some additional upside. The Asian Dollar Index rallied back up to test the region of the 200-day MA but appears to have encountered at least short-term resistance in that area and a sustained move above 118 will be required to indicate a return to demand dominance.

The background of a generally stronger Dollar may act as an additional headwind to the commodity complex. The Continuous Commodity Index has rallied back up to test the lower side of the overhead trading range and the 200-day MA. A sustained move above 620 would be required to question medium-term supply dominance.

Brent crude has been trending gradually lower since April with the most recent lower rally high near $112 on the January contract. The backwardation between the first and second months which was as high as $3 in September has contracted to 80¢ suggesting the short-term supply squeeze has moderated. A sustained move above $112 would be required to question current scope for additional lower to lateral ranging.

West Texas Intermediate Crude rallied last week to break the six-month progression of lower rally highs. It fell back to $90 today and will need to move above that level if the short-term upside is to continue to be given the benefit of the doubt.