The second-to-last day of the trading week saw ExxonMobil's (XOM -2.78%) stock jump more than 3% higher in price. This was due to a pair of factors, one external and the other internal. With that rise, ExxonMobil stock easily topped the bellwether S&P 500 index's 1.9% increase.

Peer Shell expanded its stock buyback program

Of the two catalysts, the more impactful one was the latest shareholder-pleasing move from U.K.-based peer and rival Shell. Although that company published third-quarter results that fell short of analyst estimates, it announced a dramatic expansion of its share buyback program.

That $3.5 billion initiative will be in force over the next three months and will bring the total buyback amount to $6.5 billion for the second half of 2023.

That's notably above the $5 billion figure the energy giant announced at its capital markets day in June. It also shows that the global oil and gas industry continues to reap mountains of cash. Shell, ExxonMobil, and other industry majors are fortunate to be operating in such a prosperous environment.

The Denbury acquisition closed

Separately, ExxonMobil announced that it had closed its latest asset purchase. The company said that it has sewn up its acquisition of a smaller peer, Denbury. The $4.9 billion, all-stock deal was described by ExxonMobil (quoting CEO Darren Woods) as "a major step forward in the profitable growth of our low carbon solutions business."

The acquirer said that with Denbury in its portfolio, it now holds the largest owned and operated CO2 pipeline network in this country.