A factual error spouted by Google's new AI chatbot has seen parent company Alphabet's value dive by $US100 billion ($144 billion).
An uninspired presentation on the new chatbot, called Bard, combined with longtime competitor Microsoft launching an attack on the dominant search engine saw parent company Alphabet stock price plummet by 7.7 per cent.
In an advertisement for Bard, the bot is asked: "What new discoveries from the James Webb Space Telescope can I tell my 9-year-old about?"
A number of answers are given, including one where Bard responds with a suggestions that the JWST was used to take the very first pictures of a planet outside the Earth's solar system, or exoplanets.
However NASA has confirmed the first pictures of exoplanets were taken by the European Southern Observatory's Very Large Telescope in 2004.
A Google spokesperson said the ad error highlighted the "importance of a rigorous testing process, something that we're kicking off this week with our Trusted Tester program."
"We'll combine external feedback with our own internal testing to make sure Bard's responses meet a high bar for quality, safety and groundedness in real-world information," the spokesperson said.
The stock drop marked the steepest one-day decline since October, when an Alphabet earnings report disclosed a slowdown in digital ad revenue that rattled investors.
Those concerns have escalated since another report released last week revealed Google's ad sales during the holiday season quarter fell from the same time in the previous year.
Microsoft's campaign for search engine dominance
Google's presentation for Bard contrasted with a much more polished and well-reviewed showcase of Microsoft's plans to incorporate the already popular chatbot, ChatGPT, into its Bing search engine.
By contrast, Microsoft shares were up 0.5 per cent after the announcement.
"It's not like this is the end of the world for Google and Microsoft is going to eat its lunch in search," Center for Financial Research and Analysis (CFRA) analyst Angelo Zino said.
"But ChatGPT is showing there is possible threat, and that is causing a lot of fear."
Google has been focusing on artificial intelligence for the past six years, but has been cautious about how it uses the technology in its search engine that holds a roughly 90% share of the internet market — in part because it's counted on as a go-to source for reliable information.
Although ChatGPT has attracted millions of users since its release late last year by OpenAI, it still makes glaring mistakes that would be mocked if they showed up in Google's search results. But Microsoft's Bing search engine has such a small sliver of the market that it can afford to experiment with what is still a largely untested technology.