Refining margins strengthened in the third quarter, a trend expected to benefit Ampol (ASX:ALD) more than Viva Energy Group (ASX:VEA) due to the smaller size of Ampol's refining operations, Jefferies said in an Oct. 17 note.

The Minas211 regional refining margin improved in the third quarter, rising to $14.5 per barrel from $12.6 per barrel. This rise was caused by a combination of tight refined product supply and favorable lower costs for crude oil resulting from increased OPEC+ supply and easing Middle East tensions.

Viva Energy and Ampol scheduled maintenance for their Australian refineries in the third quarter, which is expected to negatively impact their refining margins and crude intake, according to Jefferies.

Both companies are expected to provide third-quarter updates in the coming weeks.

Jefferies maintained a buy rating and AU$34 price target on Ampol. The firm has a hold rating on Viva Energy with a reduced price target of AU$1.95 from AU$2.20.

Ampol's shares fell nearly 1% in afternoon trade Monday, while Viva Energy's shares fell past 1%.