On Monday evening, oil giant ExxonMobil (XOM -2.30%) was officially removed from the Dow Jones Industrial Average. The company had been a member of the index since 1928, when it was still known as the Standard Oil Company of New Jersey. 

The change leaves ExxonMobil's fellow oil major Chevron (CVX -1.74%) as the only oil and gas company in the Dow.

A frowning man watches an oil drum spill oil onto the floor.

Image source: Getty Images.

Tech beats oil

The shakeup was prompted by the upcoming 4:1 stock split of Apple (AAPL 0.06%). Unlike the S&P 500, in which components are weighted by market cap, the Dow is calculated based on its components' share prices. Apple's new cheaper price will give it -- and by extension, the tech sector -- less weight in the index. To compensate, the Dow swapped out business software company Salesforce for ExxonMobil.

With ExxonMobil's exit, it will be the first time since 2008 that the oil and gas industry has only had one representative on the flagship index. It's a sign of how far ExxonMobil's stock has fallen over the past decade. The company's shares are down 28.4% over the last ten years, to just over $42/share. Meanwhile, Chevron -- despite having a lower market cap -- has a higher share price, of more than $87/share.

To correct its weighting, the Dow swapped out two other companies as well: biotech company Amgen replaces pharmaceutical giant Pfizer, while industrial conglomerate Honeywell replaces aerospace company Raytheon Technologies. The changes will go into effect before the market opens on August 31.