Sierra
Enterprise AI company providing Agent OS and related tools for building, deploying and improving customer-facing AI agents across chat, voice and digital channels.
Key stats
- $1.3B
- $150M
- 13
- —
- 0
- 8
- Oct 7, 2026
- Products
- 756 employees
- 53 open roles
- 40 % of Fortune 50
Recent releases
Oct 7, 2026Sierra open roles snapshotOpen roles
A third-party company tracker listed 53 open roles at Sierra.
Sep 28, 2026Ghostwriter expands to Slack and TeamsFeature update
Sierra expanded Ghostwriter into Slack and Microsoft Teams as an always-on, proactive and asynchronous teammate.
Aug 7, 2026Sierra launches Voice PersonasProduct launch
Sierra launched Voice Personas so companies can design how an agent expresses a distinct brand personality.
Jul 16, 2026Sierra launches Horizon AgentsProduct launch
Sierra launched long-horizon agents that orchestrate inbound and outbound interactions over days or weeks using persistent context and planning.
May 4, 2026Sierra serves over 40% of the Fortune 50User count
Sierra reported serving more than 40% of the Fortune 50, with agents on its platform powering billions of customer interactions.
May 4, 2026Sierra raises $950MFunding round
Sierra raised $950 million from new and existing investors led by Tiger Global and GV.
Mar 31, 2026Sierra headcount estimateEmployee count
Revelio Labs estimated Sierra's workforce at approximately 756 employees in the first quarter of 2026.
Mar 25, 2026Sierra introduces GhostwriterProduct launch
Sierra introduced an agent that creates, executes and continuously improves other customer-experience agents from described outcomes.
Upcoming
Nothing scheduled.
AI valuation history
Models
| Model | Released | Open source | ||||||
|---|---|---|---|---|---|---|---|---|
| No models recorded. | ||||||||
Platforms & products
| Name | Type | Category | Launched | Status |
|---|---|---|---|---|
| Sierra Voice Personas | Product | Voice AI | Aug 2026 | active |
| Horizon Agents | Product | Long Horizon Agents | Jul 2026 | active |
| Ghostwriter | Product | Agent Builder | Mar 2026 | active |
| Sierra Agent Data Platform | Product | Agent Memory | Nov 2025 | active |
| Sierra Agent Studio | Product | Agent Builder | Sep 2025 | active |
| Sierra Voice | Product | Voice AI | Oct 2024 | active |
| Sierra Agent OS | Platform | AI Agent Platform | Feb 2024 | active |
| Sierra Agent SDK | Product | Agent SDK | — | active |
Sources
- Oct 7, 2026 · Sierra open roles snapshotThe Consensus
- Sep 28, 2026 · Ghostwriter expands to Slack and TeamsSierra
- Aug 7, 2026 · Sierra launches Voice PersonasSierra
- Jul 16, 2026 · Sierra launches Horizon AgentsSierra
- May 4, 2026 · Sierra serves over 40% of the Fortune 50Sierra
- May 4, 2026 · Sierra raises $950MSierra
- Mar 31, 2026 · Sierra headcount estimateRevelio Labs
- Mar 25, 2026 · Sierra introduces GhostwriterSierra
- Feb 6, 2026 · Sierra exceeds $150M ARRSierra
- Nov 21, 2025 · Sierra reaches $100M ARRSierra
- Nov 5, 2025 · Sierra launches Agent Data PlatformSierra
- Nov 5, 2025 · Sierra launches Agent OS 2.0Sierra
- Nov 5, 2025 · Sierra launches Agent Studio 2.0Sierra
- Sep 18, 2025 · Sierra launches Agent StudioSierra
- Sep 4, 2025 · Sierra reports hundreds of enterprise customersSierra
- Sep 4, 2025 · Sierra raises $350MSierra
- Oct 6, 2024 · Sierra launches VoiceSierra
- Feb 13, 2024 · Sierra launches Agent OSSierra
* Market cap / valuation. Company values are AI-attributed: the latest market cap or valuation × the share attributed to AI (100% for pure AI companies). Methodology