Sierra: Building AI Agents for Enterprise Customer Experience
Sierra is an enterprise AI platform that lets companies deploy AI agents to handle customer interactions across voice and chat, while connecting to business systems and taking actions on behalf of customers.
Visit sierra.ai ↗Basic Information
| Field | Detail |
|---|---|
Company Name |
Sierra |
Category |
Enterprise AI |
Subcategory |
AI Agents, Customer Experience & Conversational AI |
Founded |
2024 |
Headquarters |
San Francisco, California, United States |
Stage |
Series E |
Total Funding |
More than $1.5 billion |
Latest Funding |
$950 million · Series E · May 2026 |
Latest Valuation |
More than $15 billion · May 2026 |
Founders |
Bret Taylor & Clay Bavor |
CEO |
Bret Taylor |
Key Investors |
Tiger Global, GV, Benchmark, Sequoia Capital, Greenoaks, ICONIQ & Thrive Capital |
Enterprise Reach |
More than 40% of the Fortune 50 reported as customers in May 2026 |
Website |
sierra.ai ↗ |
What Sierra Does
Sierra helps enterprises deploy AI agents that can communicate with customers through natural conversations and complete tasks across connected business systems. Its agents are designed to resolve customer requests rather than simply answer questions.
Key Strengths
- AI agents for customer service across chat and voice
- Integrations with enterprise systems and business workflows
- Agents that can execute actions rather than only provide information
- Enterprise deployment across regulated and complex industries
- Agent OS and tools for building and improving customer-facing agents
Why It Matters
Sierra is part of the shift from traditional chatbots toward autonomous software agents that can understand customer requests, reason across business context and complete transactions inside enterprise systems.
Sierra at Scale
40%+
Fortune 50 Reach
Sierra reported in May 2026 that more than 40% of the Fortune 50 were customers.
$150M
ARR Milestone
Sierra said it reached $150 million in annual recurring revenue by February 2026.
Billions
Customer Interactions
Sierra reported that agents built on its platform were powering billions of customer interactions by May 2026.
Enterprise Momentum
Customer Service Automation
Sierra’s agents handle use cases including insurance claims, mortgage refinancing, order returns, roadside assistance, account support and other complex customer-service workflows.
Multi-Industry Adoption
Sierra reports customers across financial services, healthcare, telecommunications, retail and consumer services, including large enterprises with complex operational requirements.
Beyond Customer Support
Sierra is expanding its agents beyond traditional support toward sales, engagement and other parts of the customer lifecycle. In 2026, the company also introduced Ghostwriter for creating specialized agents.
Agent Platform
Agent OS
Sierra’s Agent OS is designed to help customer experience teams and developers build, deploy and improve enterprise AI agents.
Voice & Chat
Sierra supports customer interactions across conversational channels, including voice and chat, allowing agents to operate across different customer touchpoints.
Agent as a Service
Ghostwriter allows users to describe an agent in natural language and generate a specialized agent for a particular business task.
Funding Journey
May 2023
Series A
$25M
Early institutional funding
February 2024
Series B
$110M
Nearly $1B valuation
October 2024
Series C
$175M
$4.5B valuation
September 2025
Series D
$350M
$10B valuation
Latest Funding & Growth
$950M Series E
In May 2026, Sierra announced a $950 million Series E led by Tiger Global and GV. The financing valued the company at more than $15 billion and brought total capital raised to more than $1 billion.
Rapid Revenue Growth
Sierra reported $100 million in ARR in November 2025 and $150 million in ARR by February 2026, reflecting rapid expansion of enterprise deployments.
Global Expansion
Sierra has expanded its presence beyond the United States, including offices and operations across Europe and Asia as it targets a global enterprise customer base.