Cloud security startup Upwind has raised $400 million at a $3.8 billion valuation after turning down an offer to be bought by Datadog, TechCrunch and Globes report.

Bessemer Venture Partners led the Series C round. Existing backers, including Greylock Partners and Craft Ventures, also took part, the outlets report. Globes reports Canapi Ventures joined as a new investor.

The round came nine months after Upwind raised $250 million at a $1.5 billion valuation, TechCrunch reports.

Datadog, a public company that sells tools to monitor how software runs, tried to buy Upwind during the funding talks. TechCrunch reports, citing a person familiar with the company, that Datadog did not offer more than the $3.8 billion value set by investors. So Upwind chose to stay independent. Globes describes the Datadog offer as about $4 billion.

Upwind uses AI to protect cloud systems in real time. Its yearly recurring revenue has grown quickly as AI-driven cyberattacks rise. TechCrunch reports, citing a person familiar with its finances, that it is on track to end the year at about $90 million. Globes reports the company puts that figure at $80 million or more and says it has quadrupled since January.

"AI is fundamentally transforming cloud infrastructure architecture," said Amiram Shachar, Upwind's cofounder and chief executive. He earlier sold his startup Spot.io to NetApp for $450 million.

TechCrunch reports Upwind still draws buyout interest. With few cybersecurity firms going public lately, a sale remains the most likely outcome, TechCrunch says. It reached out to Upwind and Datadog for comment.

What we know: Upwind raised $400 million at a $3.8 billion value and stayed independent.
What we don't: Whether Upwind will later sell to Datadog or another buyer.