NEW YORK (TheStreet) -- I was talking to Jim Cramer today about the latest moves in the oil market. This summer, the most important one seems to be the rise in the price of West Texas Intermediate crude, at least in relation to the price of Brent crude, the global benchmark. This continues to be very bad news for the refiners and the refining sector

I made a strong call two weeks ago that the price difference between these two benchmarks of crude would begin to shrink and ultimately disappear. Slowly but surely this is beginning to happen, and the WTI/Brent spread is in now close to $5.

The major reason this spread has reversed is the relatively small ruling of the U.S. Commerce Department allowing the export of lightly distilled condensate from Pioneer Natural Resources (PXD) and Enterprise Product Partners (EPD) . This ruling not only opens the door for more special dispensations to export crude oil but perhaps a full-on end of the export ban of domestically produced crude oil.

An end to the export ban would also end the massive margin advantage the U.S. refining sector has enjoyed for the last five years, in essence buying cheaper WTI crude and selling refined gasoline using the higher Brent benchmark to price refined products. It was that advantage that has spurred many of the refiners to increase three- and four-fold in the last four years. Once that margin advantage is gone, the refinery stocks will have to again revert to a more marginal valuation. That process has just begun.

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