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SierraConversational AI agents for customer experience; founded by OpenAI Chair Bret Taylor
Valuation (May 2026 Series D)
$15.8B
+58% from $10B (Oct 2025)
Annualized Revenue (2026)
~$200M
$150M Feb 2026; $100M Nov 2025
Customer Reach
>40% of Fortune 50
agents handle billions of interactions across CX verticals
Founder Pedigree
Bret Taylor (OpenAI Chair)
Former Salesforce co-CEO, Facebook CTO, Google Maps co-creator; current OpenAI Board Chair
Total raised: ~$1.6B · Latest valuation: $15.8B
| Round | Date | Amount | Valuation | Key Investors |
|---|---|---|---|---|
| Seed / Series A | Feb 2024 | $110M (cumulative) | $1B | Benchmark (lead)SequoiaRavi Gupta (Benchmark)Pat Grady (Sequoia) |
| Series B | Oct 2024 | $175M | $4.5B | Greenoaks (lead)BenchmarkSequoiaThrive Capital+1 more |
| Series C | Oct 2025 | $350M | $10B | Greenoaks (lead, per The Information)SequoiaThrive CapitalICONIQ |
| Series D | May 2026 | $950M | $15.8B | Tiger Global (co-lead)GV (co-lead)BenchmarkSequoia+1 more |
| Product | Type | Status |
|---|---|---|
| Sierra Agent Platform | Build + deploy + monitor conversational AI agents (chat + voice) | GA |
| AgentOS | Runtime + observability + guardrails for production agents | GA |
| Voice Agents | Phone-channel conversational AI with sub-second latency | GA (Feb 2025) |
| Sierra Benchmark / TAU 2.0 | Open-source agent-evaluation benchmark | Released |
| Agent Outcomes | Outcome-based pricing tied to resolution / containment / CSAT | GA |
Model-agnostic; routes per task; Bret Taylor's OpenAI board role drives no exclusivity.
Subscription + listener support across the SiriusXM and Pandora brands.
Customer support for the troubled 2024 app launch and ongoing.
Coaching + member-support agent; one of the first Sierra reference deployments.
Home-security customer service; high-stakes / regulated vertical.
Regulated-industry agent deployments.
DTC and home-services reference customers.
Bret Taylor (former Salesforce co-CEO, current OpenAI Board Chair) and Clay Bavor (former Google VP, Project Starline) launch Sierra
Sierra exits stealth at $1B valuation; first customers (WeightWatchers, SiriusXM, Sonos, ADT) revealed
Sierra's platform for building, deploying, monitoring conversational agents in regulated and high-CX verticals
Greenoaks leads $175M, 4.5x the Series A valuation in 8 months
Native voice support added; targets phone-channel customer service in addition to chat
Open-source benchmark for evaluating agent quality; standardizes how Sierra customers measure ROI
Per The Information; 2.2x the Series B valuation, ~24 months from founding to decacorn
Crosses $100M annualized revenue seven quarters after launch
$950M co-led by Tiger Global and GV; claims more than 40% of the Fortune 50 as customers
Customer-experience AI agents. Founded by Bret Taylor (Salesforce, OpenAI board chair) and Clay Bavor (ex-Google). Customers include WeightWatchers, Sonos, SiriusXM. Series, late 2024, raised $175M at a $4.5B valuation led by Sequoia and Benchmark. Sierra was founded in 2023, is headquartered in San Francisco, CA and employs ~300.
Sierra has raised ~$1.6B in total at a $15.8B valuation, based on the funding rounds Sterling tracks.
Sterling groups Sierra in the AI Software sector, alongside Harvey (private), Decagon (private), SoundHound AI (SOUN), Veritone (VERI) and Axon Enterprise (AXON).
If you are researching Sierra, also look at SoundHound AI (SOUN), Veritone (VERI) and Axon Enterprise (AXON). You can compare all of them side by side or browse the full AI Software sector on Sterling.
