Revenue during the quarter surged 52.60 percent to $3,080.48 million from $2,018.72 million in the previous year period. Gross margin for the quarter contracted 840 basis points over the previous year period to 13.88 percent. Operating margin for the quarter stood at negative 1.06 percent as compared to a positive 4.14 percent for the previous year period.

Operating loss for the quarter was $32.72 million, compared with an operating income of $83.60 million in the previous year period.

However, the adjusted EBITDA for the quarter stood at $85.46 million compared with $96.05 million in the prior year period. At the same time, adjusted EBITDA margin contracted 198 basis points in the quarter to 2.77 percent from 4.76 percent in the last year period.

HollyFrontier's president & chief executive officer, George Damiris, commented, "First quarter crude rate was negatively impacted by our planned turnaround at Navajo, planned maintenance at the El Dorado vacuum tower, unplanned maintenance at the Tulsa CCR reformer, and the crude supply pipeline outage to our Woods Cross refinery. We are pleased with the results from the Navajo turnaround and the efficiency and debottleneck projects that were implemented during the turnaround. During the Tulsa outage, we were able to accelerate other maintenance and a catalyst upgrade originally planned for later this year, all of which will allow us to benefit from higher liquid yields and octane during the summer driving season. We are also encouraged by the results we have begun to see from our focused efforts to improve operations and reliability at Cheyenne; crude rate was over 48,000 barrels per day in March. With no major planned downtime until November, our refineries are well positioned for strong operational and financial performance for the remainder of the year."