The market capitalization of the world's five-largest publicly traded oil and gas companies declined by US$92.07 billion in the third quarter, according to data compiled by S&P Global Market Intelligence.
That figure represents an 8.3% decline in the value of the shares of those companies. Meanwhile, some independent oil and gas producers and oilfield services companies that round out the sector's 25 largest U.S., European and Canadian companies saw steeper declines.
Oil and gas producer EOG Resources Inc. saw its market cap plunge 20.3%, while that of oilfield services company Schlumberger Ltd. fell 14.0%.

Analysts have cited skepticism in capital discipline, low oil prices and disappointing free cash flow for the flight of capital away from oil and gas stocks. Against that backdrop, the price impact of an approximate 5% disruption in global oil supply brought by an attack on Saudi Arabian oil infrastructure was only fleeting, and oil and gas stocks moved lower in tandem with the oil market as the Saudis restored oil production more quickly than expected.
In the third quarter, survey results released by the Federal Reserve Bank of Dallas showed a decline in oilfield service activity in the region where U.S. tight oil production growth is fastest. Exxon Mobil Corp., which remained at the top of the list, warned that it expects third-quarter profits to be down nearly 50% year over year on oil price weakness.
Twenty-four of 25 companies remained on the list from the prior quarter, with MPLX LP replacing Pioneer Natural Resources Co., whose market cap declined 18.9%, bringing its rank among the group from 25th place to 28th place. MPLX closed on its $9 billion acquisition of Andeavor Logistics on July 30.
During the quarter, oil and gas refining and marketing stocks such as Marathon Petroleum Corp. and Phillips 66 helped to offset the declines seen in the broader oil and gas sector. Analysts expect that tighter marine fuel sulfur standards and persisting discounts for heavy Canadian crude oil will boost the profitability of U.S. refiners through the end of 2020.

The S&P 500 Energy Index saw a total return of negative 6.3% during the third quarter, underperforming the S&P 500, which posted a total return of 1.7%.
