Crack spread is a term used on the oil industry and futures trading for the differential between the price of crude oil and petroleum products extracted from it, use to determine profit margin for refining company. 

For reference, Petronas Dagangan Just Reported Superb Quarter Earning

Petronas Dagangan Bhd

(Aug 21, RM26.64)

Maintain buy with a higher target price (TP) of RM30.08: Petronas Dagangan Bhd’s (PetDag) second quarter of financial year 2018 (2QFY18) reported earnings surged by 41.5% year-on-year (y-o-y) to RM314.4 million. On a quarterly sequential basis, revenue was supported by higher average selling price (ASP) of 5% offset by lower sales volume of 1%.

 
The cumulative six months (6MFY18) earnings accounted for 53.6% and 52.8% of our and consensus full-year FY18 earnings estimates respectively.

Retail segment profitability increased in line with increasing Mean of Platts Singapore (MOPS) price. In addition, lower product and freight costs also contributed to higher margin for motor gas, diesel and retail liquefied petroleum gas (LPG). However, this was partially offset by higher spending on advertising and promotion.