For several years, Exxon Mobil has been the world’s most valuable company on the stock market. But now Apple, the U.S. consumer technology company, is contesting the oil giant’s claim to the top spot.

On Wednesday, for the first time, Apple held on to the No. 1 spot when the stock market closed for the day. As trading ended Wednesday, Exxon was valued at about $330 billion and Apple at a little more than $337 billion.

Apple, the maker of the popular iPhones, iPads and Macintosh computers, had briefly surpassed Exxon a day earlier, but the oil company had regained the lead by the end of trading Tuesday.

Financial analysts say the values of the two companies are likely to continue to fluctuate, perhaps more so for Exxon, as the worth of its oil holdings continues to rise and fall on world markets. After the U.S. central bank, the Federal Reserve, decided Tuesday to keep its benchmark interest rate at a historically low level for the next two years, oil prices edged higher again and continued upward on Wednesday. That boosted Exxon’s fortunes.

Apple’s march to near the top has been fraught with corporate missteps followed by marked success. In the 1990s, it was a relatively minor player in the technology industry and flirted with bankruptcy. But Apple transformed itself from a personal computer manufacturer into a company producing the trendy iPhone and the iPad tablet for audio-visual media.