Sierra

Bret Taylor's company builds enterprise AI agents that perform customer-facing work, over chat and voice, rather than merely answering questions. Customers include SiriusXM, ADT, Sonos and major banks and retailers, and Sierra charges by outcome rather than per seat.

• Valued at $10B in September 2025.
• Voice agents now handle a large share of customer calls for several enterprise customers.
• Outcome-based pricing is becoming the template for enterprise agents.

Sierra is the strongest proof that AI agents can replace entire customer-service operations, with the executive pedigree (Taylor chairs OpenAI's board) to win enterprise trust.

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