ExxonMobil Corp. continues to reign supreme as the world’s top energy enterprise and has regained its title as the largest domestic publicly traded entity.

In its annual ranking of the world’s leading public energy companies by market capitalization, PFC Energy 50 on Monday said the Irving, TX-based supermajor was No. 1 for the second year in a row. PFC’s listing of 100 top energy companies overall breaks down the largest listed energy firms from nine sectors: international oil companies; national oil companies; exploration and production (E&P); natural gas/utilities; oilfield services; equipment, engineering and construction; midstream/infrastructure; refining and marketing; and alternative technologies.

The combined market capitalization of the top 50 companies was $3.5 trillion at the end of last year., about equal (down 0.8%) to the group’s value at the end of 2011. Some of the biggest gainers were based in North America, where unconventional oil and natural gas production has “radically” changed the energy picture, PFC researchers said. Last year the North American oil and refining sector showed strong gains, as had the natural gas sector before that.

“The unconventional oil and gas story in North America continues to impact company values in new and surprising ways,” PFC’s researchers noted. The huge surge in U.S. oil output over the past year was noticeable.

“Geography played a key role,” noted PFC, with oil-focused companies linked to the Bakken Shale and Canadian oilsands outperforming their global competitors. “Differentials between coastal and inland crude prices widened in 2012 as a lack of infrastructure to move crude to global markets created discounts as wide as $30-50/bbl between more landlocked oil and West Texas Intermediate/Brent.”

North America’s unconventional prizes continue to impress through volume growth and investment interest, but creating value has been more elusive, noted PFC. For instance, the top 15 E&Ps, which are dominated by companies with big North American portfolios, also are heavily natural gas-weighted, and they “showed an average decline of 4% in share price as markets continued to punish weak gas prices.”

According to the top 50 list, ExxonMobil in 2012 had a market capitalization (cap) of $394.6 billion. The second, third and fourth spots repeated from 2011 as well: PetroChina International Ltd., $264.5 billion; Royal Dutch Shell plc, $222.6 billion; and Chevron Corp., $211.6 billion.

BP plc gained one spot to No. 5 with $132.1 billion in market cap, while Colombia’s Ecopetrol SA leapfrogged into No. 6 from No. 12 with $126.6 billion. Brazil’s Petroleo Brasileiro SA was seventh, down two, at $124.7 billion, followed by France’s Total SA (No. 8 both years) at $121.9 billion. Russia’s Gazprom OAO dropped two spots to No. 9 at $112.3 billion, while China Offshore Oil Co. Ltd. was at No. 10, up five, with a market cap of $96.7 billion.

Other North American energy companies to make the top 50 were Schlumberger Ltd., which fell two spots to No. 13 at $92 billion; ConocoPhillips, down six to No. 16, $70.4 billion; Suncor Energy Inc., No. 20 again, $50.4 billion; Enterprise Products Partners, up one to No. 24, $45.1 billion; Anadarko Petroleum Corp. down one to No. 27, $37.1 billion; Imperial Oil Ltd., up one at No. 28, $36.5 billion; and Enbridge Energy Partners LP, No. 29 from No. 40, $34.7 billion.

At No. 31, up six spots, was TransCanada Corp. at $33.4 billion, while ConocoPhillips’ 2012 spinoff Phillips 66 moved into the No. 32 spot at $33.2 billion. EOG Resources Inc. gained nine spots to No. 33 with $32.7 billion; Halliburton Ltd. remained at No. 34 with $32.2 billion; Canadian Natural Resources Ltd. fell 10 to No. 36 at $29.8 billion; and National Oilwell Varco Inc. dropped one to No. 39 with $29.2 billion.

Canada’s Husky Oil Ltd. gained eight spots to No. 40 with a market cap of $29.1 billion, while Kinder Morgan Inc. fell two spots to No. 43 at $28.2 billion. Also in the top 50 was Cenovus Energy Inc., which fell four spots to No. 48 with a market cap of $25.3 billion.

ExxonMobil also regained its top spot among U.S. market capitalization last week, toppling Apple Inc.; the two have traded positions over the past two years. Apple attained the largest market cap in U.S. market history in 2011 when it was worth about $660 billion. A sell-off early this year has led to a drop-off of close to $200 billion.

However, Motley Fool analyst Eric Bleeker said Friday market cap comparisons are “silly” because they don’t incorporate total returns. ExxonMobil outshines Apple now, but “it’s been returning cash to shareholders since 1882 when it was part of Standard Oil…and has increased its dividend for 30 straight years.”

The implication, said Bleeker, is that when a company pays out a dividend, “that actually decreases its market cap as that capital is sent to its shareholders. Exxon has paid out over $75 billion to shareholders in the past decade and repurchased $190 billion of its own stock. Today it has $13 billion in cash.

“Without returning that capital across the past decade, the company would have $278 billion in cash sitting around. Such a figure would make Apple’s much-discussed $137 billion cash hoard look puny in comparison.”