Sierra Hits $15.8B Valuation in $950M Round as Bret Taylor Races to Lock Up Enterprise AI

Sierra, the AI customer-experience startup co-founded by OpenAI chair and former Salesforce co-CEO Bret Taylor, has raised $950 million in a Series E round at a post-money valuation of more than $15 billion — a near doubling from the $10 billion mark it set just last fall. The round was led by Tiger Global and Google's GV, with participation from Benchmark, Sequoia, Greenoaks and other existing investors. Taylor said in a post on X that the company now has more than $1 billion to invest in becoming "the global standard for companies wanting to transform their customer experiences with AI."

The growth numbers behind the round are eye-popping by traditional software standards. Sierra hit $100 million in annual recurring revenue in late November and reached $150 million ARR by early February, a milestone the company says no traditional software firm has ever crossed in just eight quarters. Penetration into the Fortune 50 now exceeds 40%, with customers including Prudential, Cigna, Blue Cross Blue Shield and Rocket Mortgage. Sierra agents already handle billions of interactions per year — refinancing mortgages, processing insurance claims, managing returns and even running nonprofit fundraising — territory that until recently was the exclusive preserve of human contact-center staff.

The fundraise lands as Sierra rolls out Ghostwriter, an "agent as a service" tool launched in April that lets customers describe what they need in natural language and have an autonomous agent built and deployed for them. That product expansion, combined with what Taylor framed as a need to "invest aggressively so we can continue to expand our lead," helps explain why a company already at nine-figure ARR is still raising on this scale. The new capital is widely expected to fund deeper R&D on multi-agent orchestration and a global sales push beyond Sierra's existing North American base.

Taylor was unusually candid about what he sees coming for the rest of the agentic-AI sector. He told investors he expects a market correction within the next two years and predicted a "culling effect" in which capital dries up for everyone except a handful of category leaders. The implicit pitch to LPs: bet on the breakaway, not the field. With OpenAI surpassing $25 billion in annualized revenue and Anthropic approaching $19 billion, Sierra's bet is that customer-experience agents will be the first agentic vertical where one or two enterprise platforms consolidate the market — and that the next 18 months are when those platforms will be picked.