Microsoft is nipping at the heels of longtime leader Apple, in the never-ending race to be the largest U.S. company.

Why it matters: It's another sign of how the emergence of artificial intelligence is prompting a reshuffling of the giant tech companies that dominate the market and heavily influence the U.S. economy.

Driving the news: In an otherwise sleepy session Thursday, the market value of Apple and Microsoft briefly crisscrossed before noon, after which Microsoft faded and left America's corporate league tables unchanged by the end of trading.

• Both companies are worth just a touch under $2.9 trillion, according to FactSet data.

Context: The see-saw battle for the top spot reflects Microsoft's AI-fueled romp higher — it's up more than 60% over the last 12 months, compared to Apple's roughly 40%.

• Apple is also facing headwinds on reports that the Department of Justice is preparing a broad-ranging antitrust case against it.

Be smart: Microsoft is a backer of OpenAI, the maker of ChatGPT, and the creator of the AI platform Copilot. It is considered well-positioned for the AI boom that many investors and analysts view as a near certainty over the next few years.

What they're saying: "We continue to believe this is a '1995 Moment' with a transformational tech spending wave not seen since the start of the Internet in the mid 90's with AI now hitting the shores of the tech sector," wrote tech analyst Dan Ives, of brokerage firm Wedbush, in a December research note.

This story was updated with closing market values.