Three major AI startup rounds in May 2026: Parag Agrawal's Parallel Web Systems hits $2B valuation ($100M raised for AI agent search infra), ElevenLabs crosses $500M ARR as BlackRock and NVIDIA join its $11B Series D, and Bret Taylor's Sierra AI raises $950M at $15.8B valuation.
Parallel Web Systems, founded by ex-Twitter CEO Parag Agrawal, closed a Sequoia-led $100M Series B at a $2B valuation on April 29. The company provides search and research APIs purpose-built for AI agents, serving over 100,000 developers.
ElevenLabs disclosed $500M in ARR and $100M in net new ARR in Q1 2026 alone, as it added institutional backers including BlackRock, NVIDIA, and Deutsche Telekom to its $500M Series D originally announced in February.
Sierra, the AI customer agent platform co-founded by OpenAI board chair Bret Taylor, raised $950M in a Series E led by Tiger Global and GV at a $15.8B valuation. The company grew ARR from $100M to $150M in just three months, signaling surging enterprise demand for AI agents.