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Sierra

Category: AI Agents

An AI-powered conversational agent platform for building and deploying enterprise-grade customer service bots. Sierra was founded in 2023. The company is led by Bret Taylor. Based in San Francisco Bay Area, CA & Remote. Total funding raised: $1.585 billion. Latest round: Series C ($350.0M, 2025-09) - Sierra. Key investors include Greenoaks Capital, ICONIQ Growth, Thrive Capital, Sequoia Capital, Benchmark, Tiger Global, GV (Google Ventures).

AMW Analysis

Sierra provides a conversational AI agent platform aimed at automating enterprise customer service, combining a multi-model approach to reduce hallucinations with customizable brand-aligned personalities. Founded in 2023, the company has raised a total of $1.585 billion, with backing from investors including Sequoia Capital, Benchmark, Greenoaks Capital, ICONIQ Growth, Thrive Capital, Tiger Global, and GV. Its news flow over the tracked period shows rapid, sequential capital raises alongside an accelerating acquisition strategy: after reaching a $10 billion valuation in January 2026, Sierra raised $950 million in a Series E led by Tiger Global and GV in May 2026, lifting its valuation to $15.8 billion, and closed a further $350 million Series C in September 2025. Alongside this funding, Sierra has pursued M&A to broaden its product suite, acquiring Opera Tech, a Tokyo-based AI contact center startup, months after opening a Japan office, and most recently acquiring Takeoff, launching a joint "Horizon" platform for long-running, outcome-driven enterprise agents. Reported customer usage includes over 40% of the Fortune 50 and deployments spanning mortgage, insurance, and other enterprise workflows.

AMW analysis, generated from 8 tracked news signals.

Founded
2023
Headquarters
San Francisco Bay Area, CA & Remote
Total funding
$1.585 billion

Value proposition

Automates complex customer service tasks end-to-end, reduces AI hallucinations using a multi-model approach, and offers customizable brand-aligned personalities.

Products and solutions

Generative AI-powered conversational agents, Integration layer connecting multiple large language models (from OpenAI, Anthropic, Meta, etc.), Ghostwriter (agent-building agent, launched March 2026), Agent OS 2.0 (with Agent Studio 2.0, Agent Data Platform, Live Assist), Voice agents (primary channel since Oct 2025)

Unique value

Utilizes a 'constellation' of multiple large language models to cross-check for accuracy and reduce hallucinations. Offers deep customization of the AI agent's personality to align with brand identity.

Target customer

Large enterprises requiring sophisticated, automated customer service solutions.

Industries served

Financial Services, Healthcare, Telecommunications, Media & Entertainment, Travel and Hospitality, Retail and Consumer Goods, Technology, Home Security

Technology advantage

Deep integration with enterprise backend systems to perform actions, not just provide answers. The leadership team's extensive experience at top tech companies (Salesforce, Google, Facebook).

How they differentiate

Focuses on premium, action-oriented automation rather than just Q&A. Claims significantly lower hallucination rates due to its multi-LLM architecture.

Main competitors

Ada, Intercom, Zendesk

Key partnerships

OpenAI, Anthropic, Meta, SoftBank Vision Fund 2

Notable customers

WeightWatchers, SiriusXM, Sonos, ADT, Casper, Prudential, Cigna, Blue Cross Blue Shield, Rocket Mortgage, Chime, Nordstrom, Nubank, Ramp, Rivian, Singtel, Sutter Health, Wayfair, Redfin, DIRECTV, Gap, Hyvee, Safelite

Major milestones

Launched publicly in February 2024 after operating in stealth mode., Announced raising $110 million in combined seed and Series A funding in February 2024., Secured a $175 million Series B funding round in October 2024, reaching a $4.5 billion valuation., Onboarded major enterprise clients including WeightWatchers, SiriusXM, Sonos, and ADT., Hit $100M ARR in 7 quarters (November 2025)., Raised $350M Series C at $10B valuation (September 2025)., Hit $150M ARR in 8 quarters (February 2026)., Launched Ghostwriter agent-building tool (March 2026)., Acquired Opera Tech (Tokyo) and Fragment (Paris) for international expansion (March-April 2026)., Raised $950M Series E at $15.8B valuation led by Tiger Global and GV (May 2026).

Growth metrics

Reached $150M+ ARR in 8 quarters (Feb 2026). Valued at $15.8 billion post-money following Series E in May 2026. Serves 40%+ of the Fortune 50. Agents built on Sierra touch 95% of US shoppers.

Market positioning

A premium, high-end solution targeting large, complex enterprises.

Geographic focus

Primarily US-based, serving global brands.

Patents and IP

Information not publicly available

About Bret Taylor

Bret Taylor is a distinguished software engineer and industry leader with a 20-year history of building widely-used products. He is the co-founder and CEO of Sierra, a conversational AI platform. Previously, he was the Co-CEO of Salesforce. He also founded Quip, which was acquired by Salesforce. Before that, he was the CTO of Facebook and started his career at Google, where he co-created Google Maps. He also serves as the chairman of the board at OpenAI.

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