Sierra Closes $950M Series E at $15.8B: Bret Taylor's Enterprise AI Agent Startup Wins 40% of Fortune 50

$150M ARR, 40% Fortune 50 Penetration

Sierra announced a $950 million Series E on May 4, 2026, led by Tiger Global and Google's GV, with Benchmark, Sequoia, Greenoaks, and other existing investors participating. The round values the company at $15.8 billion post-money.

The company was co-founded by Bret Taylor (OpenAI board chair, former Salesforce co-CEO) and Clay Bavor (former Google executive) three years ago. Sierra builds AI-powered customer service agents that automate mortgage refinancing, insurance claims, and customer support at scale. More than 40% of the Fortune 50 are customers. ARR reached $150 million in early 2026, up from $100 million in late November 2025 — 50% growth in roughly three months.

Why the Timing Matters

The round lands one week after both Anthropic and OpenAI separately launched enterprise AI joint ventures. Enterprise AI is no longer a future bet — companies are buying software that replaces operational headcount at scale. Taylor said: "We now have more than $1 billion to invest in becoming the global standard for companies wanting to transform their customer experiences with AI."

Source: TechCrunch, CNBC