Upwind Lands $400M Series C at $3.8B After Rejecting Datadog's $3.8B No-Premium Buyout

Cloud and AI security startup Upwind closed a $400M Series C at a $3.8B valuation led by Bessemer, after turning down a Datadog acquisition offer at the same valuation with no premium. Revenue has quadrupled in 2026 to roughly $90M ARR, and Upwind's valuation has risen from $1.5B in January, backed by its runtime-security approach that deploys specialized AI agents to investigate and remediate alerts across workloads, APIs and other AI agents.