Anthropic's revenue is growing fast -- but perhaps not fast enough for a company targeting a $2 trillion valuation.

That was the worry for investors after details from the Claude large-language model developer's private investor day on Wednesday failed to meet the market's sky-high expectations.

The big takeaway was that sales growth is slowing. Anthropic's revenue rose 45% to $16.8 billion for the third quarter, The Wall Street Journal reported -- down from a triple-digit jump in the second quarter.

Anthropic didn't immediately respond to a request for comment from Barron's.

When it goes public, Anthropic is likely to serve as an AI bellwether.

So the deceleration in quarterly revenue growth doesn't bode well for the AI trade at a time when investors were already fretting about rising interest rates and ballooning debt, with the recent slump in shares of cloud-computing company CoreWeave summing up those fears.

True to form, AI stocks were struggling again on Thursday. Chip makers AMD and Micron, flash-memory supplier Sandisk, and hard-drive makers Seagate and Western Digital all dropped around 3% to 4% in premarket trading.

The slowdown in Anthropic's revenue growth doesn't have to cripple the AI trade. It's possible that some money flipped to Anthropic's rival OpenAI, or Meta Platforms' personal AI agent Muse -- rather than leaving the sector completely.

But whatever the course, the AI trade is being severely tested Thursday as a number of long-held fears mount all at once.