Anthropic’s growth slowed and costs jumped in the third quarter, updated IPO filing shows

Anthropic’s revenue kept climbing in the third quarter of 2026, but at a slower pace, according to an amended IPO prospectus for the company published on the U.S. Securities and Exchange Commission website Monday.

During its third quarter, Anthropic generated $17 billion in revenue for the three months ended September 30, the company said in its new filing. That’s up from $11.6 billion in the second quarter and $1.4 billion a year earlier. Anthropic’s third quarter financial results were left out of the company’s initial IPO prospectus , also known as a S-1 filing, when it was published last week. The document has now been amended to include the latest quarterly figures.

While the lab’s sales are still growing rapidly—increasing more than 1,000% year over year—the pace of that growth has slowed from the second quarter. The company’s revenue grew about 47% in the three months ended on Sept. 30, down from about 144% growth in the prior three months.

A surge in computing costs also pushed the AI company back into an operating loss, the filing showed.

Total operating expenses rose to $17.5 billion from $10.6 billion in the second quarter. This resulted in Anthropic reporting an operating loss of $567 million, after reporting a $974 million operating profit the quarter before. The company attributes that loss primarily to compute bought under short-term commitments, which noted in the filing “currently costs significantly more” than compute secured under its multi-year deals. The company also cites $2 billion in non-cash charges tied to an employee donation matching program.

Strip out stock-based pay and those charitable charges, however, and Anthropic’s business is still profitable on an adjusted basis, with the dollar amount of those profits edging up slightly from the second quarter. But the company’s adjusted operating margins have shrunk, largely because of that pricier short-term compute. The company said its adjusted operating margin the third quarter was 15%, down from 19% in the second quarter.

The expensive short-term compute may also help explain why Anthropic is seeking to lock in long-term data center capacity at an enormous scale. The filing discloses that the company has committed to about $895.4 billion in spending, most of which is being used for compute and infrastructure. Much of that relates to Anthropic Direct , its own dedicated infrastructure, which the company says will let it replace short-term compute with cheaper long-term capacity as it comes online.