(Reuters) - Exxon Mobil Corp
"I think the (earnings) shortfall was across the board," Brian Youngberg, oil analyst at Edward Jones in St Louis. "The biggest miss was on the downstream, the refining margins were well below expectations."
The world's largest publicly traded oil company reported profit at $6.9 billion, or $1.55 per share, down 57 percent from $15.9 billion, or $3.41 per share in the same period a year earlier.
Analysts on average had forecast a profit of $1.90 per share, according to Thomson Reuters I/B/E/S.
Oil and natural gas production fell 1.9 percent.
Profit in Exxon's refining business was $396 million, down sharply from $6.6 billion in the 2012 second quarter. Year-ago results included a $5.3 billion gain related to restructuring in Japan, but weaker margins and maintenance also weighed on results, Exxon said.
Shares of Exxon edged down 1 percent to $92.40 in premarket trading.
(Reporting By Anna Driver; Editing by Marguerita Choy and Sofina Mirza-Reid)