Diesel's retail margin is down 72 cents a gallon in a month, to $1.015

The spread between what retail diesel sells for and what it costs at wholesale is 1.015 now, down 0.724 over the past 30 days. That is about 72 cents a gallon of margin gone in a month. Wholesale cost climbed faster than the street price, and anyone buying diesel to resell is working on a much thinner cut than they were four weeks ago.

The pressure came from the barrel. ULSD diesel futures are 4.095, up 28.9% over 30 days, the biggest move of any product on our board, and the contract is high in its range at the 71 percent mark. Crude did the pushing: Brent is 96.78, up 31.2%, and WTI is 89.31, up 27.0%. Refiners captured that move rather than absorbing it. The 3:2:1 crack spread is 59.07, up 4.25 over the same 30 days, so the refinery margin widened while the retail diesel margin shrank. The barrel and the plant both gained ground here; the pump is the part that lost it.

Gasoline tells the calmer version of the same story. RBOB is 3.252, up 12.8%, and sitting near the middle of its range at 49 percent, so the crude run has hit diesel far harder than gasoline. If you sell both, watch the diesel side more closely than gasoline this week.

Diesel is priced high while the retail side has not caught up, which is what a 1.015 spread with futures at 71 percent of range is telling you. That could ease if street prices follow wholesale up, or if crude backs off and takes the futures down with it. Either way the diesel margin is the number to watch, and right now it is the one working against you.