Sierra Raises $950M at $15.8B Valuation as Enterprise AI Agent Spend Goes Mainstream

Sierra, the AI customer-service agent startup co-founded by OpenAI chairman Bret Taylor, raised $950 million at a $15.8 billion valuation in a round led by Tiger Global and GV, with Benchmark, Sequoia, and Greenoaks also participating. The company says ARR hit $150 million in early February, up from $100 million in late November, and that it now sells into more than 40% of the Fortune 50 — Prudential, Cigna, Blue Cross Blue Shield, and Rocket Mortgage among the named customers. The signal here is not Sierra itself but what enterprise buyers are doing with their support and CRM budgets: large insurers and lenders are routing real interaction volume through agent platforms now, not pilots. For small teams on Zendesk, Intercom, or HubSpot, expect your incumbent vendors to ship Sierra-style autonomous agents on higher tiers within the next 12 months, often as upsells rather than replacements — check the Zapier review for where DIY agent stacks fit. The honest caveat: $15.8B post-money is priced for near-perfect execution, and Sierra's recent Ghostwriter agent-builder puts it on a collision course with Salesforce and ServiceNow.