Sierra, an AI startup based in Silicon Valley and co-founded by Bret Taylor—former Salesforce co-CEO and current OpenAI Chairman—has raised $175 million in a recent funding round, pushing its valuation to $4.5 billion.

Led by Greenoaks Capital with contributions from Thrive Capital and Iconiq, this latest investment follows an earlier $110 million round backed by Sequoia Capital and Benchmark.

Founded by Taylor, credited for co-creating Google Maps, and former Google executive Clay Bavor, Sierra specializes in AI-driven customer service chatbots for enterprise clients.

The startup’s technology aims to reduce “hallucinations,” a common challenge where AI models produce inaccurate information, giving Sierra a unique edge in the competitive AI customer service space.

According to Reuters, Sierra’s impressive client roster includes WeightWatchers and Sirius XM. In just a year, the company has reached over $20 million in annualized revenue, demonstrating rapid growth and market relevance in a sector shifting toward practical AI applications over foundational model development.

This funding round underscores growing investor enthusiasm for enterprise-focused AI applications, particularly those with strong, seasoned leadership and a commercialized approach to AI solutions.