Oct 3 (Reuters) -

A slump in oil prices probably reduced Exxon Mobil's ( XOM )

third-quarter upstream earnings by $600 million to $1 billion,

the oil major signaled in a regulatory filing published on

Thursday.

Oil prices fell by 17% in the third quarter, the largest

quarterly decline in a year, on worries about the

global oil demand outlook. Brent futures settled at

$71.77 a barrel on the last trading day of the quarter.

The company, in its earnings snapshot, indicated weaker

refining margins during the quarter would also hurt profits by

up to $1 billion. Global fuel markets have been hit by softer

consumer and industrial demand, especially in China where

economic growth is slowing and electric vehicle use is on the

rise.

Shares of Exxon closed at $122.58 each on Thursday. They

were up just a 1 cent in after hours trading.

Exxon posted $7.07 billion in upstream earnings for the

second quarter and a net profit of $9.1 billion in the year-ago

third quarter, or $2.25 per share.

Analysts expect the industry giant to post an adjusted

profit of $1.97 per share in the third quarter, according to

estimates compiled by LSEG.