Sierra

Sierra builds an enterprise platform for conversational AI agents that handle customer service across chat, voice, email, SMS and other channels, branded and tuned for each company's needs. Founded in 2024 by former Salesforce co-CEO Bret Taylor and Clay Bavor, it targets large enterprises and counts a substantial share of the Fortune 50 among its customers, with reported ARR above $150M. The company is headquartered in San Francisco and operates a London office serving the UK and Europe. It raised a $950M Series E in May 2026 at a $15.8B valuation, with total funding exceeding $1.5B from investors including Benchmark, Sequoia, Greenoaks, Tiger Global and GV.